fix: Add context manager return types (#43)

* docs: Add documentation for enums

fix: Add context manager return types

chore: Update gapic-generator-python to v1.8.1
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google/cloud/api_keys_v2/services/api_keys/client.py

@@ -1358,7 +1358,7 @@ def sample_lookup_key():
         # Done; return the response.
         return response
 
-    def __enter__(self):
+    def __enter__(self) -> "ApiKeysClient":
         return self
 
     def __exit__(self, type, value, traceback):

samples/generated_samples/snippet_metadata_google.api.apikeys.v2.json

@@ -8,7 +8,7 @@
     ],
     "language": "PYTHON",
     "name": "google-cloud-api-keys",
-    "version": "0.5.0"
+    "version": "0.1.0"
   },
   "snippets": [
     {