CI-CD: Fix gh release target

`gh release --target` no longer accepts a full ref
(and has never allowed a tag). It needs either
a branch or a sha.

Author: medmunds

.github/workflows/release.yml

@@ -76,7 +76,7 @@ jobs:
           NOTES: |
             [Changelog](https://anymail.dev/en/stable/changelog/#${{ steps.version.outputs.anchor }})
         run: |
-          if ! gh release edit "$TAG" --verify-tag --target "$GITHUB_REF" --title "$TITLE" --notes "$NOTES"; then
-            gh release create "$TAG" --verify-tag --target "$GITHUB_REF" --title "$TITLE" --notes "$NOTES"
+          if ! gh release edit "$TAG" --verify-tag --target "$GITHUB_SHA" --title "$TITLE" --notes "$NOTES"; then
+            gh release create "$TAG" --verify-tag --target "$GITHUB_SHA" --title "$TITLE" --notes "$NOTES"
           fi
           gh release upload "$TAG" ./dist/*