fix(deps): require protobuf <4.0.0dev (#95)

Author: parthea

setup.py

@@ -40,7 +40,8 @@
  include_package_data=True,
  install_requires=(
  "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",
  ),
  python_requires=">=3.6",
  classifiers=[

testing/constraints-3.6.txt

@@ -8,3 +8,4 @@
 google-api-core==1.31.5
 proto-plus==1.15.0
 libcst==0.2.5
+protobuf==3.19.0