try fix CD

Author: Stephan Dilly

.github/workflows/cd.yml

@@ -49,6 +49,7 @@ jobs:
         echo ::set-output name=sha::"$(shasum -a 256 ./release/gitui-mac.tar.gz | awk '{printf $1}')"
 
     - name: Extract release notes
+      if: matrix.os == 'ubuntu-latest'
       id: release_notes
       uses: ffurrer2/extract-release-notes@v1
     - name: Release