ci: update pull request workflow to install libssl1.1 before testing the subgraph

Author: vplasencia

.github/workflows/pull-requests.yml

@@ -135,6 +135,7 @@ jobs:
             - if: steps.changed-files.outputs.subgraph_any_changed == 'true'
               name: Build and Test Subgraph
               run: |
+                  sudo apt-get update && sudo apt-get install -y libssl1.1
                   yarn workspace @semaphore-protocol/utils build
                   yarn build:subgraph
                   yarn test:subgraph