fix: refresh anyio package in lowest-direct resolution tests

The CI was failing for lowest-direct tests due to cache corruption
where anyio 4.5.0 was being installed with mixed files from anyio 4.10.0.
This occurred because the cache was shared between the "highest" tests
(which install anyio 4.10.0 from the lockfile) and "lowest-direct" tests
(which resolve to anyio 4.5.0).

The symptom was that anyio's _backends/_asyncio.py tried to import
RunFinishedError (which only exists in anyio 4.11+), but the
_exceptions.py file was from anyio 4.5.0 (which doesn't have it),
causing ImportError.

This fix adds --refresh-package anyio to lowest-direct tests, forcing
anyio to be revalidated from PyPI while keeping the cache enabled for
other packages.

Github-Issue: #1325

Author: felixweinberger

.github/workflows/shared.yml

@@ -39,7 +39,7 @@ jobs:
         python-version: ["3.10", "3.11", "3.12", "3.13"]
         dep-resolution:
           - name: lowest-direct
-            install-flags: "--resolution lowest-direct"
+            install-flags: "--resolution lowest-direct --refresh-package anyio"
           - name: highest
             install-flags: "--frozen"
         os: [ubuntu-latest, windows-latest]