[ruff-ecosystem] Fix CLI crash on Python 3.14 (#21092)

Author: danparizher

.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

python/ruff-ecosystem/ruff_ecosystem/cli.py

@@ -87,7 +87,8 @@ def entrypoint():
     )
 
     with cache_context as cache:
-        loop = asyncio.get_event_loop()
+        loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(loop)
         main_task = asyncio.ensure_future(
             main(
                 command=RuffCommand(args.ruff_command),

scripts/check_ecosystem.py

@@ -528,7 +528,8 @@ async def limited_parallelism(coroutine: T) -> T:
     else:
         logging.basicConfig(level=logging.INFO)
 
-    loop = asyncio.get_event_loop()
+    loop = asyncio.new_event_loop()
+    asyncio.set_event_loop(loop)
     if args.checkouts:
         args.checkouts.mkdir(exist_ok=True, parents=True)
     main_task = asyncio.ensure_future(