ci: Mark Python 3.11 as experimental

The-Compiler · The-Compiler · commit 6fc30a1e851d · 2022-04-26T17:14:38.000+02:00
end2end tests seem flaky, no clue why
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
@@ -129,6 +129,7 @@ jobs:
           - testenv: py311-pyqt515
             os: ubuntu-20.04
             python: "3.11-dev"
+            experimental: true
           ### macOS: PyQt 5.15 (Python 3.9 to match PyInstaller env)
           - testenv: py39-pyqt515
             os: macos-10.15
