[TASK] Adding extension key detection again

With recent change on the publis workflow the
extension key detection has been accedently
dropped.

This change reintroduces the detection.

Author: sbuerk

Diff for: .github/workflows/publish.yml

@@ -45,6 +45,7 @@ jobs:
             echo "https://github.com/fgtclb/academic-persons/releases/tag/${{ env.version }}"
             echo EOF
           } >> "$GITHUB_ENV"
+          echo "DETECTED_EXTENSION_KEY=$(cat composer.json | jq -r '.extra."typo3/cms"."extension-key"' )" >> "$GITHUB_ENV"
 
       - name: Setup PHP 7.4 ( wv_deepltranslate 4.x )
         if: github.event.base_ref == 'refs/heads/4'