Bump andymckay/append-gist-action

Bumps [andymckay/append-gist-action](https://github.com/andymckay/append-gist-action) from 1fbfbbce708a39bd45846f0955ed5521f2099c6d to 6e8d64427fe47cbacf4ab6b890411f1d67c07f3e.
- [Release notes](https://github.com/andymckay/append-gist-action/releases)
- [Commits](andymckay/append-gist-action@1fbfbbc...6e8d644)

---
updated-dependencies:
- dependency-name: andymckay/append-gist-action
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/junit.yml

@@ -72,7 +72,7 @@ jobs:
 
       - name: Upload badge to Gist
         if: github.ref == 'refs/heads/master'
-        uses: andymckay/append-gist-action@1fbfbbce708a39bd45846f0955ed5521f2099c6d
+        uses: andymckay/append-gist-action@6e8d64427fe47cbacf4ab6b890411f1d67c07f3e
         with:
           token: ${{ secrets.GIST_TOKEN }}
           gistURL: https://gist.githubusercontent.com/eclipse-releng-bot/78d110a601baa4ef777ccb472f584038