chore(deps): update dependency protobuf to v3.19.4 (googleapis#1169)

Co-authored-by: Dov Shlachter <[email protected]>

Author: renovate-bot

requirements.txt

@@ -3,7 +3,7 @@ google-api-core==2.1.1
 googleapis-common-protos==1.54.0
 jinja2==3.0.3
 MarkupSafe==2.0.1
-protobuf==3.19.3
+protobuf==3.19.4
 pypandoc==1.7.2
 PyYAML==6.0
 dataclasses==0.6  # TODO(busunkim) remove when 3.6 support is dropped