Disable pypy311

Despite the suite succeeding as noted in
e9483d8, github sucks so it still
marks a PR / commit as failing if non-required tests fail (red cross
on the commit and "Some checks were not successful" on the PR), which
sucks.

Not to mention pypy311 does not exist yet, let alone being provided by
setup-python, so it can never succeed.

Therefore remove it.

.github/workflows/ci.yml

@@ -89,7 +89,7 @@ jobs:
           - "pypy-3.8"
           - "pypy-3.9"
           - "pypy-3.10"
-          - "pypy-3.11"
+          # - "pypy-3.11"
         include:
           - source: sdist
             artifact: dist/*.tar.gz