feat: allow Python 3.10 (#417)

* feat: allow Python 3.10

* add missing test configs

* 🦉 Updates from OwlBot

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

Author: tswast

setup.py

@@ -77,6 +77,7 @@
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",
+        "Programming Language :: Python :: 3.10",
         "Operating System :: OS Independent",
         "Topic :: Internet",
         "Topic :: Scientific/Engineering",
@@ -85,7 +86,7 @@
     packages=packages,
     install_requires=dependencies,
     extras_require=extras,
-    python_requires=">=3.7, <3.10",
+    python_requires=">=3.7, <3.11",
     include_package_data=True,
     zip_safe=False,
 )