remove obsolete fields from slack notification

.github/workflows/release.yml

@@ -171,9 +171,7 @@ jobs:
           text: 'Version <https://github.com/${{ github.repository }}/releases/tag/${{ steps.extract_variables.outputs.TAG }}|${{ steps.extract_variables.outputs.TAG }}> of the <https://api.datacite.org|REST API> has been released to production and test.'
           failure_text: '${env.GITHUB_WORKFLOW} (${env.GITHUB_RUN_NUMBER}) build failed'
           fields: |
-            [{ "title": "Commit message", "value": "${{ github.event.head_commit.message }}" },
-             { "title": "Committed by", "value": "<https://github.com/${{ github.repository }}/commits?author=${{ github.actor }}|${{ github.actor }}>", "short": true },
+            [{ "title": "Committed by", "value": "<https://github.com/${{ github.repository }}/commits?author=${{ github.actor }}|${{ github.actor }}>", "short": true },
              { "title": "Commit SHA", "value": "<https://github.com/${{ github.repository }}/commit/${{ steps.extract_variables.outputs.GIT_SHA }}|${{ steps.extract_variables.outputs.GIT_SHA_SHORT }}>", "short": true },
              { "title": "Repository", "value": "<https://github.com/${{ github.repository }}|${{ github.repository }}>", "short": true },
-             { "title": "Branch", "value": "<https://github.com/${{ github.repository }}/tree/${{ steps.extract_variables.outputs.BRANCH }}|${{ steps.extract_variables.outputs.BRANCH }}>", "short": true },
              { "title": "Release", "value": "<https://github.com/${{ github.repository }}/releases/tag/${{ steps.extract_variables.outputs.TAG }}|${{ steps.extract_variables.outputs.TAG }}>", "short": true }]