fix(build): migrate to using main branch (#71)

Author: Benjamin E. Coe

.github/.OwlBot.lock.yaml

@@ -1,3 +1,3 @@
 docker:
   image: gcr.io/repo-automation-bots/owlbot-nodejs:latest
-  digest: sha256:6245a5be4c0406d9b2f04f380d8b88ffe4655df3cdbb57626f8913e8d620f4dd
+  digest: sha256:72ff93409133b0cf277b8870f859e1ddde62d2e329f655311d4bfc16735d182e

.github/generated-files-bot.yml

@@ -8,9 +8,9 @@ generatedFiles:
 - path: '.github/generated-files-bot.+(yml|yaml)'
   message: '`.github/generated-files-bot.(yml|yaml)` should be updated in [`synthtool`](https://github.com/googleapis/synthtool)'
 - path: 'README.md'
-  message: '`README.md` is managed by [`synthtool`](https://github.com/googleapis/synthtool). However, a partials file can be used to update the README, e.g.: https://github.com/googleapis/nodejs-storage/blob/master/.readme-partials.yaml'
+  message: '`README.md` is managed by [`synthtool`](https://github.com/googleapis/synthtool). However, a partials file can be used to update the README, e.g.: https://github.com/googleapis/nodejs-storage/blob/main/.readme-partials.yaml'
 - path: 'samples/README.md'
-  message: '`samples/README.md` is managed by [`synthtool`](https://github.com/googleapis/synthtool). However, a partials file can be used to update the README, e.g.: https://github.com/googleapis/nodejs-storage/blob/master/.readme-partials.yaml'
+  message: '`samples/README.md` is managed by [`synthtool`](https://github.com/googleapis/synthtool). However, a partials file can be used to update the README, e.g.: https://github.com/googleapis/nodejs-storage/blob/main/.readme-partials.yaml'
 ignoreAuthors:
 - 'gcf-owl-bot[bot]'
 - 'yoshi-automation'

.github/workflows/ci.yaml

@@ -1,7 +1,7 @@
 on:
   push:
     branches:
-      - master
+      - main
   pull_request:
 name: ci
 jobs:

.kokoro/continuous/node10/common.cfg

@@ -6,7 +6,7 @@
 
 [![release level](https://img.shields.io/badge/release%20level-beta-yellow.svg?style=flat)](https://cloud.google.com/terms/launch-stages)
 [![npm version](https://img.shields.io/npm/v/@google-cloud/artifact-registry.svg)](https://www.npmjs.org/package/@google-cloud/artifact-registry)
-[![codecov](https://img.shields.io/codecov/c/github/googleapis/nodejs-artifact-registry/master.svg?style=flat)](https://codecov.io/gh/googleapis/nodejs-artifact-registry)
+[![codecov](https://img.shields.io/codecov/c/github/googleapis/nodejs-artifact-registry/main.svg?style=flat)](https://codecov.io/gh/googleapis/nodejs-artifact-registry)
 
 
 
@@ -15,7 +15,7 @@ Artifactregistry client for Node.js
 
 
 A comprehensive list of changes in each version may be found in
-[the CHANGELOG](https://github.com/googleapis/nodejs-artifact-registry/blob/master/CHANGELOG.md).
+[the CHANGELOG](https://github.com/googleapis/nodejs-artifact-registry/blob/main/CHANGELOG.md).
 
 * [Artifact Registry Node.js Client API Reference][client-docs]
 * [Artifact Registry Documentation][product-docs]
@@ -85,11 +85,11 @@ listsRepositories();
 
 ## Samples
 
-Samples are in the [`samples/`](https://github.com/googleapis/nodejs-artifact-registry/tree/master/samples) directory. Each sample's `README.md` has instructions for running its sample.
+Samples are in the [`samples/`](https://github.com/googleapis/nodejs-artifact-registry/tree/main/samples) directory. Each sample's `README.md` has instructions for running its sample.
 
 | Sample                      | Source Code                       | Try it |
 | --------------------------- | --------------------------------- | ------ |
-| Quickstart | [source code](https://github.com/googleapis/nodejs-artifact-registry/blob/master/samples/quickstart.js) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/nodejs-artifact-registry&page=editor&open_in_editor=samples/quickstart.js,samples/README.md) |
+| Quickstart | [source code](https://github.com/googleapis/nodejs-artifact-registry/blob/main/samples/quickstart.js) | [![Open in Cloud Shell][shell_img]](https://console.cloud.google.com/cloudshell/open?git_repo=https://github.com/googleapis/nodejs-artifact-registry&page=editor&open_in_editor=samples/quickstart.js,samples/README.md) |
 
 
 
@@ -132,19 +132,19 @@ More Information: [Google Cloud Platform Launch Stages][launch_stages]
 
 ## Contributing
 
-Contributions welcome! See the [Contributing Guide](https://github.com/googleapis/nodejs-artifact-registry/blob/master/CONTRIBUTING.md).
+Contributions welcome! See the [Contributing Guide](https://github.com/googleapis/nodejs-artifact-registry/blob/main/CONTRIBUTING.md).
 
 Please note that this `README.md`, the `samples/README.md`,
 and a variety of configuration files in this repository (including `.nycrc` and `tsconfig.json`)
 are generated from a central template. To edit one of these files, make an edit
-to its template in this
-[directory](https://github.com/googleapis/synthtool/tree/master/synthtool/gcp/templates/node_library).
+to its templates in
+[directory](https://github.com/googleapis/synthtool).
 
 ## License
 
 Apache Version 2.0
 
-See [LICENSE](https://github.com/googleapis/nodejs-artifact-registry/blob/master/LICENSE)
+See [LICENSE](https://github.com/googleapis/nodejs-artifact-registry/blob/main/LICENSE)
 
 [client-docs]: https://cloud.google.com/nodejs/docs/reference/artifact-registry/latest
 [product-docs]: https://cloud.google.com/artifact-registry/