Test PyPy 3.11 (#334)

PyPy 3.11 is the currently supported version.

Perhaps we should get rid of PyPy 3.9 and 3.10, but let's defer to
a later PR or commit.

Co-authored-by: Mike Fiedler <[email protected]>

Author: DimitriPapadopoulos

.github/workflows/ci.yml

@@ -9,6 +9,7 @@ jobs:
         python-version:
           - "pypy-3.9"
           - "pypy-3.10"
+          - "pypy-3.11"
           - "3.9"
           - "3.10"
           - "3.11"

tox.ini

@@ -1,7 +1,7 @@
 [tox]
 envlist =
     py{39, 310, 311, 312, 313, 314}
-    pypy{39, 310}
+    pypy{39, 310, 311}
     pep8
     packaging
     noextra