Fixup cache key for GA: prefer matrix.os

Change-Id: I43684ca1900c41934a244e2be810f7358419d07e

Author: Synss

.github/workflows/pr.yaml

@@ -17,6 +17,7 @@ jobs:
       PYTHONWARNINGS: ignore:DeprecationWarning
     strategy:
       matrix:
+        os: [ubuntu-24.04]
         include:
         - name: Bandit tests
           target: test-bandit
@@ -46,7 +47,7 @@ jobs:
     - name: Cache uv
       uses: actions/cache@v3
       with:
-        key: uv-$ImageOS-${{ hashFiles('requirements_all_lock.txt') }}
+        key: uv-${{ matrix.os }}-${{ hashFiles('requirements_all_lock.txt') }}
         path: ${{ env.UV_CACHE_DIR  }}
     - name: Setup Environment
       run: |