Promote pyproject beta to production/stable (#14777)

Will land this PR and cherry-pick to release/1.0 branch as we approach
to 1.0 release.

Author: mergennachin

pyproject.toml

@@ -31,7 +31,7 @@ classifiers = [
     #   3 - Alpha
     #   4 - Beta
     #   5 - Production/Stable
-    "Development Status :: 4 - Beta",
+    "Development Status :: 5 - Production/Stable",
     "Intended Audience :: Developers",
     "Intended Audience :: Education",
     "Intended Audience :: Science/Research",