Declare support for Python 3.11 (#2018)

(cherry picked from commit a394c90)

Author: hugovk

pyproject.toml

@@ -24,6 +24,7 @@ classifiers = [
     "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
+    "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: Implementation :: CPython",
     "Programming Language :: Python :: Implementation :: PyPy",
     "Topic :: Software Development :: Libraries :: Python Modules",