Limit Docker tests to Linux

Author: s1hofmann

.github/workflows/snapshot.yaml

@@ -78,7 +78,7 @@ jobs:
         with:
           run: npm run coverage -- --coverageDirectory=coverage/unit
       - name: Run Docker E2E tests
-        if: ${{matrix.os === 'ubuntu-latest'}}
+        if: ${{matrix.os == 'ubuntu-latest'}}
         run: docker exec nut-ci bash -c "bash $PWD/.build/build.sh ${PWD} 14"
 
   deploy: