ci/tests: skip downstream tests on pypy

.github/workflows/.tests-matrix.yaml

@@ -69,7 +69,8 @@ jobs:
   pytest-poetry:
     name: pytest (Poetry)
     runs-on: ${{ inputs.runner }}
-    if: inputs.run-pytest-poetry
+    # FIXME: make Poetry tests pass with PyPy
+    if: inputs.run-pytest-poetry && !startsWith(inputs.python-version, 'pypy')
     steps:
       - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
         with: