appveyor: add Python 3.11 (#63)

Co-authored-by: Panos <pkittenis@users.noreply.github.com>

Author: enkore

.appveyor.yml

@@ -32,7 +32,7 @@ environment:
     PYTHON_DEF: "C:\\Python38-x64"
     PYTHON_VERSION: "3.8"
     # Python versions to build wheels for
-    PYTHONVERS: C:\Python36-x64 C:\Python37-x64 C:\Python38-x64 C:\Python39-x64 C:\Python310-x64
+    PYTHONVERS: C:\Python36-x64 C:\Python37-x64 C:\Python38-x64 C:\Python39-x64 C:\Python310-x64 C:\Python311-x64
     PYTHON_ARCH: "64"
 
 install: