Check pkg-config

Author: alcaeus

.github/workflows/system-libs.yml

@@ -46,3 +46,7 @@ jobs:
         shell: bash
         working-directory: /tmp
         run: cmake --install _build --prefix "/usr/share/pkgconfig" --config RelWithDebInfo
+
+      - name: Check pkg-config availability
+        shell: bash
+        run: pkg-config --modversion mongoc2