Run tests with coverage only with Python3.12

Coverage is not working with Python3.11 since the COVERAGE_CORE setting
was added by !31.  Disable coverage run for Python3.11 as we only need
coverage to run for one Python version, preferably the latest.

Closes #3

.github/workflows/ci.yaml

@@ -24,7 +24,13 @@ jobs:
         run: |
              python -m pip install -U pip
              python -m pip install tox
-      - name: Run Tox
+      - name: Run Tox without coverage
+        if: matrix.python != '3.12'
+        run: tox
+        env:
+            TOXENV: py${{ matrix.python-version}}
+      - name: Run Tox with coverage
+        if: matrix.python == '3.12'
         run: tox
         env:
             TOXENV: py${{ matrix.python-version}}-cov-codecov