add tmate action debugging (#512)

Enable by triggering a manual test run. See https://github.com/marketplace/actions/debugging-with-tmate
[skip ci]

.github/workflows/test-suite.yml

@@ -1,6 +1,13 @@
 name: test-suite
 
-on: [pull_request]
+on:
+  workflow_dispatch:
+    inputs:
+      debug_enabled:
+        description: 'Run the tests with tmate debugging enabled'
+        required: false
+        default: 'false'
+  pull_request:
 
 env:
   db_password: 'postgres'
@@ -17,6 +24,10 @@ jobs:
     steps:
     - uses: actions/checkout@v2
 
+    - name: Setup tmate session
+      uses: mxschmitt/action-tmate@v3
+      if: ${{ github.event_name == 'workflow_dispatch' && github.event.inputs.debug_enabled }}
+
     - uses: webfactory/[email protected]
       with:
         ssh-private-key: ${{ secrets.FORCED_PHOT_DEPLOY_KEY }}