fix: set UV_RESOLUTION=highest for highest tests to avoid empty value

Setting UV_RESOLUTION to empty string causes uv to fail with
'a value is required for --resolution' error.

Author: felixweinberger

.github/workflows/shared.yml

@@ -59,7 +59,8 @@ jobs:
       - name: Run pytest
         run: uv run ${{ matrix.dep-resolution.install-flags }} --no-sync pytest
         env:
-          UV_RESOLUTION: ${{ matrix.dep-resolution.name == 'lowest-direct' && 'lowest-direct' || '' }}
+          # Set UV_RESOLUTION for lowest-direct so test subprocesses use same strategy
+          UV_RESOLUTION: ${{ matrix.dep-resolution.name == 'lowest-direct' && 'lowest-direct' || 'highest' }}
 
   readme-snippets:
     runs-on: ubuntu-latest