fix: pin gherkin version

debug: screenshot use firefox

.github/workflows/_screenshot.yml

@@ -9,7 +9,7 @@ on:
       browser:
         required: false
         type: string
-        default: chrome
+        default: firefox
       url:
         required: true
         type: string

.github/workflows/manual_e2e.yml

@@ -28,7 +28,7 @@ jobs:
       with:
         python-version: '3.10'
     - name: 'Install gherkin-official'
-      run: 'pip install gherkin-official'
+      run: 'pip install gherkin-official==30.0.4'
     - name: 'Generate checklist'
       run: 'python features/_convert.py'
     - name: 'Add checklist comment'