Try different install prefix

Author: alcaeus

.github/workflows/system-libs.yml

@@ -45,7 +45,7 @@ jobs:
       - name: Install libmongoc
         shell: bash
         working-directory: /tmp
-        run: cmake --install _build --prefix "/usr/share/pkgconfig" --config RelWithDebInfo
+        run: cmake --install _build --prefix "/usr/local" --config RelWithDebInfo
 
       - name: Check pkg-config availability
         shell: bash