[ruff-ecosystem] Fix CLI crash on Python 3.14

[danparizher]

Summary

Fixed the Python 3.14 crash in ruff-ecosystem by updating event loop handling.

Fixes #20965

Changes Made

1. python/ruff-ecosystem/ruff_ecosystem/cli.py (line 90-91)

• Replaced asyncio.get_event_loop() with asyncio.new_event_loop() and asyncio.set_event_loop(loop)

2. scripts/check_ecosystem.py (line 531-532)

• Applied the same update

Why This Works

In Python 3.14, asyncio.get_event_loop() raises when no loop exists. Creating the loop explicitly ensures:

• Python 3.10+ support
• Signal handler behavior preserved
• Loop is closed in the finally block

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

Formatter (stable)

✅ ecosystem check detected no format changes.

Formatter (preview)

✅ ecosystem check detected no format changes.

[AlexWaygood]

Please can you also make this change to our workflow file, if this fixes the crash:

diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index c57773078f..131f76acad 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -531,8 +531,7 @@ jobs:
           persist-credentials: false
       - uses: astral-sh/setup-uv@d0cc045d04ccac9d8b7881df0226f9e82c39688e # v6.8.0
         with:
-          # TODO: figure out why `ruff-ecosystem` crashes on Python 3.14
-          python-version: "3.13"
+          python-version: ${{ env.PYTHON_VERSION }}
           activate-environment: true
 
       - uses: actions/download-artifact@634f93cb2916e3fdff6788551b99b062d0335ce0 # v5.0.0

[MichaReiser]

Thank you.