chore: regenerate README (#295)

This PR was generated using Autosynth. 🌈


<details><summary>Log from Synthtool</summary>

```
2020-10-20 08:16:26,170 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-containeranalysis/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working directory clean
2020-10-20 08:16:27,223 synthtool [DEBUG] > Wrote metadata to .github/readme/synth.metadata/synth.metadata.

```
</details>

Full log will be available here:
https://source.cloud.google.com/results/invocations/17746cb7-5060-42fe-a1ec-431813af8242/targets

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Author: yoshi-automation

.github/readme/synth.metadata/synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-containeranalysis.git",
-        "sha": "6d86df1aa13415f9f8adae542eabe45fcac39d90"
+        "sha": "82a053420fd363561c6a088006fe83eb7cc988bf"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "27e0e916cbfdb3d5ff6639b686cc04f78a0b0386"
+        "sha": "5a506ec8765cc04f7e29f888b8e9b257d9a7ae11"
       }
     }
   ]

README.md

@@ -45,11 +45,11 @@ If you are using Maven without BOM, add this to your dependencies:
 
 If you are using Gradle, add this to your dependencies
 ```Groovy
-compile 'com.google.cloud:google-cloud-containeranalysis:1.2.2'
+compile 'com.google.cloud:google-cloud-containeranalysis:1.2.3'
 ```
 If you are using SBT, add this to your dependencies
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-containeranalysis" % "1.2.2"
+libraryDependencies += "com.google.cloud" % "google-cloud-containeranalysis" % "1.2.3"
 ```
 
 ## Authentication