Run Complement with workers in CI

.github/workflows/tests.yml

@@ -310,6 +310,16 @@ jobs:
     needs: linting-done
     runs-on: ubuntu-latest
 
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          # GHA requires all matrix configurations to have at least one value. We don't want to set one here though.
+          - _: monolith
+
+          # Test with workers
+          - workers: workers
+
     steps:
       # The path is set via a file given by $GITHUB_PATH. We need both Go 1.17 and GOPATH on the path to run Complement.
       # See https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#adding-a-system-path
@@ -356,7 +366,7 @@ jobs:
 
       - run: |
           set -o pipefail
-          COMPLEMENT_DIR=`pwd`/complement synapse/scripts-dev/complement.sh -json 2>&1 | gotestfmt
+          WORKERS=${{ matrix.workers && 1 }} COMPLEMENT_DIR=`pwd`/complement synapse/scripts-dev/complement.sh -json 2>&1 | gotestfmt
         shell: bash
         name: Run Complement Tests