ci: remove obsolete certificates installation on macOS

https://github.com/actions/setup-python/issues/512 has been fixed by
https://github.com/actions/python-versions/pull/189, so the workaround
is no longer necessary.

.github/workflows/main.yml

@@ -52,11 +52,6 @@ jobs:
         id: full-python-version
         run: echo ::set-output name=version::$(python -c "import sys; print('-'.join(str(v) for v in sys.version_info))")
 
-      # XXX: Certificates are not correctly installed for 3.11-dev -- remove when fixed.
-      - name: Install missing certificates on 3.11 for macOS
-        if: ${{ matrix.python-version == '3.11-dev' && matrix.os == 'macOS' }}
-        run: /Applications/Python\ 3.11/Install\ Certificates.command
-
       - name: Bootstrap poetry
         run: |
           curl -sL https://install.python-poetry.org | python - -y