fix(deps): require protobuf<4.0.0 on v1 branch (#305)

* fix(deps): require protobuf<4.0.0 on v1 branch

* chore: fix ci

* chore: fix ci

noxfile.py

@@ -25,38 +25,38 @@
 
 BLACK_VERSION = "black==19.3b0"
 BLACK_PATHS = ["docs", "google", "tests", "noxfile.py", "setup.py"]
+DEFAULT_PYTHON_VERSION = "3.8"
 
 if os.path.exists("samples"):
     BLACK_PATHS.append("samples")
 
+# Error if a python version is missing
+nox.options.error_on_missing_interpreters = True
 
-@nox.session(python="3.7")
+
+@nox.session(python=DEFAULT_PYTHON_VERSION)
 def lint(session):
     """Run linters.
 
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.install("flake8", BLACK_VERSION)
+    session.install("flake8", BLACK_VERSION, "click<8.1")
     session.run("black", "--check", *BLACK_PATHS)
     session.run("flake8", "google", "tests")
 
 
-@nox.session(python="3.6")
+@nox.session(python=DEFAULT_PYTHON_VERSION)
 def blacken(session):
     """Run black.
 
     Format code to uniform standard.
-
-    This currently uses Python 3.6 due to the automated Kokoro run of synthtool.
-    That run uses an image that doesn't have 3.6 installed. Before updating this
-    check the state of the `gcp_ubuntu_config` we use for that Kokoro run.
     """
-    session.install(BLACK_VERSION)
+    session.install(BLACK_VERSION, "click<8.1")
     session.run("black", *BLACK_PATHS)
 
 
-@nox.session(python="3.7")
+@nox.session(python=DEFAULT_PYTHON_VERSION)
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
     session.install("docutils", "pygments")
@@ -121,7 +121,7 @@ def system(session):
         session.run("py.test", "--quiet", system_test_folder_path, *session.posargs)
 
 
-@nox.session(python="3.7")
+@nox.session(python=DEFAULT_PYTHON_VERSION)
 def cover(session):
     """Run the final coverage report.
 
@@ -134,7 +134,7 @@ def cover(session):
     session.run("coverage", "erase")
 
 
-@nox.session(python="3.7")
+@nox.session(python=DEFAULT_PYTHON_VERSION)
 def docs(session):
     """Build the docs for this library."""
 

setup.py

@@ -27,6 +27,7 @@
     "google-api-core[grpc] >= 1.31.5, <3.0.0dev,!=2.0.*,!=2.1.*,!=2.2.*,!=2.3.0",
     "grpc-google-iam-v1 >= 0.12.3, < 0.13dev",
     'enum34; python_version < "3.4"',
+    "protobuf<4.0.0dev",
 ]
 
 package_root = os.path.abspath(os.path.dirname(__file__))