Fix changelog retrieval workflow step

Author: snejus

.github/workflows/make_release.yaml

@@ -56,7 +56,7 @@ jobs:
         run: sudo apt update && sudo apt install pandoc -y
 
       - name: Obtain the changelog
-        run: echo "changelog=$(poe changelog)" >> $GITHUB_OUTPUT
+        run: echo "changelog='$(poe changelog)'" >> $GITHUB_OUTPUT
 
       - name: Build a binary wheel and a source tarball
         run: poetry build