ci: install lcov in coverage summary job

Author: Simon

.github/workflows/ci.yml

@@ -109,6 +109,11 @@ jobs:
           name: openvx-build
           path: ${{ github.workspace }}
 
+      - name: Install lcov
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y lcov
+
       - name: Show coverage summary
         run: |
           lcov --summary coverage.info