feat: release as GA (#46)

Release-As: 1.0.0

[GA release template](https://github.com/googleapis/google-cloud-common/issues/287)
## Required 

- [x] 28 days elapsed since last beta release with new API surface
- [x] Server API is GA
- [x] Package API is stable, and we can commit to backward compatibility
- [x] All dependencies are GA


Fixes #14 🦕

.repo-metadata.json

@@ -4,7 +4,7 @@
     "product_documentation": "https://cloud.google.com/compute/docs/osconfig/",
     "client_documentation": "https://googleapis.dev/python/osconfig/latest",
     "issue_tracker": "",
-    "release_level": "beta",
+    "release_level": "ga",
     "language": "python",
     "repo": "googleapis/python-os-config",
     "distribution_name": "google-cloud-os-config",

README.rst

@@ -1,16 +1,16 @@
 Python Client for Cloud OS Config
 =================================================
 
-|beta| |pypi| |versions|
+|GA| |pypi| |versions|
 
 `Cloud OS Config API`_: OS management tools that can be used for patch management,
 patch compliance, and configuration management on VM instances.
 
 - `Client Library Documentation`_
 - `Product Documentation`_
 
-.. |beta| image:: https://img.shields.io/badge/support-beta-orange.svg
-   :target: https://github.com/googleapis/google-cloud-python/blob/master/README.rst#beta-support
+.. |GA| image:: https://img.shields.io/badge/support-GA-gold.svg
+   :target: https://github.com/googleapis/google-cloud-python/blob/master/README.rst#general-availability
 .. |pypi| image:: https://img.shields.io/pypi/v/google-cloud-os-config.svg
    :target: https://pypi.org/project/google-cloud-os-config/
 .. |versions| image:: https://img.shields.io/pypi/pyversions/google-cloud-os-config.svg

setup.py

@@ -29,7 +29,7 @@
 # 'Development Status :: 3 - Alpha'
 # 'Development Status :: 4 - Beta'
 # 'Development Status :: 5 - Production/Stable'
-release_status = "Development Status :: 4 - Beta"
+release_status = "Development Status :: 5 - Production/Stable"
 dependencies = [
     "google-api-core[grpc] >= 1.22.2, < 2.0.0dev",
     "proto-plus >= 1.10.0",