chore(Showcase): Update to Showcase 0.22.0 (#1362)

Co-authored-by: Anthonios Partheniou <partheniou@google.com>

Author: vchudnov-g

packages/gapic-generator/noxfile.py

@@ -29,7 +29,7 @@
 nox.options.error_on_missing_interpreters = True
 
 
-showcase_version = os.environ.get("SHOWCASE_VERSION", "0.19.0")
+showcase_version = os.environ.get("SHOWCASE_VERSION", "0.22.0")
 ADS_TEMPLATES = path.join(path.dirname(__file__), "gapic", "ads-templates")