ref: add pyi stubs for google-crc32c (#68792)

<!-- Describe your PR here. -->

fixtures/stubs-for-mypy/google_crc32c/__init__.pyi

@@ -0,0 +1,2 @@
+# TODO: can remove this after https://github.com/googleapis/python-crc32c/pull/211
+def value(bts: bytes, /) -> int: ...

pyproject.toml

@@ -96,7 +96,6 @@ module = [
     "google.cloud.*",
     "google.resumable_media.common.*",
     "google.rpc.status_pb2.*",
-    "google_crc32c.*",
     "kombu.*",
     "mistune.*",
     "onelogin.saml2.auth.*",