fix(deps): require protobuf <4.0.0dev (#391)

Author: parthea

setup.py

@@ -26,7 +26,8 @@
     # Until this issue is closed
     # https://github.com/googleapis/google-cloud-python/issues/10566
     "google-api-core[grpc] >= 1.31.5, <3.0.0dev,!=2.0.*,!=2.1.*,!=2.2.*,!=2.3.0",
-    "proto-plus >= 1.15.0",
+    "proto-plus >= 1.15.0, <2.0.0dev",
+    "protobuf >= 3.19.0, <4.0.0dev",
 ]
 extras = {
     "libcst": "libcst >= 0.2.5",

testing/constraints-3.6.txt

@@ -10,3 +10,4 @@ proto-plus==1.15.0
 libcst==0.2.5
 pandas==0.23.0
 google-cloud-storage==1.18.0
+protobuf==3.19.0