deps: update protobuf to 4.21.9 (#271)
deps: update protobuf to 4.21.9 (#271)

This is done by pip-compile.
Also charset_normalizer is downgraded to 2.1.1, which seems correct
because requests still doesn't support charset_normalizer V3.
googleapis/proto-breaking-change-detector,googleapis/proto-breaking-change-detector