Enable testing with Python 3.11 (#9511)

.github/workflows/main.yml

@@ -37,6 +37,7 @@ jobs:
           "windows-py38",
           "windows-py39",
           "windows-py310",
+          "windows-py311",
 
           "ubuntu-py36",
           "ubuntu-py37",
@@ -45,6 +46,7 @@ jobs:
           "ubuntu-py38",
           "ubuntu-py39",
           "ubuntu-py310",
+          "ubuntu-py311",
           "ubuntu-pypy3",
 
           "macos-py37",
@@ -81,6 +83,10 @@ jobs:
             python: "3.10"
             os: windows-latest
             tox_env: "py310-xdist"
+          - name: "windows-py311"
+            python: "3.11-dev"
+            os: windows-latest
+            tox_env: "py311"
 
           - name: "ubuntu-py36"
             python: "3.6"
@@ -111,6 +117,10 @@ jobs:
             python: "3.10"
             os: ubuntu-latest
             tox_env: "py310-xdist"
+          - name: "ubuntu-py311"
+            python: "3.11-dev"
+            os: ubuntu-latest
+            tox_env: "py311"
           - name: "ubuntu-pypy3"
             python: "pypy-3.7"
             os: ubuntu-latest