Add remote debug to CI runners

Signed-off-by: Nicolas Bock <nicolas.bock@canonical.com>

Author: nicolasbock

.github/workflows/tests.yaml

@@ -1,8 +1,14 @@
 name: Test
 on:
-  - push
-  - pull_request
-  - workflow_dispatch
+  push:
+  pull_request:
+  workflow_dispatch:
+    inputs:
+      debug_enabled:
+        type: boolean
+        description: 'Run the build with tmate debugging enabled (https://github.com/marketplace/actions/debugging-with-tmate)'
+        required: false
+        default: false
 
 jobs:
   test:
@@ -40,3 +46,6 @@ jobs:
     - name: Run functional
       run: tox -e functional
       if: matrix.python-version == '3.10'
+    - name: Setup tmate session
+      uses: mxschmitt/action-tmate@v3
+      if: ${{ github.event_name == 'workflow_dispatch' && inputs.debug_enabled }}