fix(ci): use ubuntu-latest in test coverage workflow (#4943)

Author: kanalsop

.github/workflows/test-cov.yml

@@ -10,7 +10,7 @@ concurrency:
 
 jobs:
   test:
-    runs-on: $ubuntu-latest
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
         with: