change file to files for codecov action

Author: bgctw

.github/workflows/CI.yml

@@ -42,7 +42,7 @@ jobs:
       - uses: julia-actions/julia-processcoverage@v1
       - uses: codecov/codecov-action@v5
         with:
-          file: lcov.info
+          files: lcov.info
           token: ${{ secrets.CODECOV_TOKEN }}
           fail_ci_if_error: true
   docs: