Upgrade to auto changelog 1.2 (#621)

diff --git a/.github/workflows/update-changelog.yml b/.github/workflows/update-changelog.yml
index a220896..4f1f176 100644
--- a/.github/workflows/update-changelog.yml
+++ b/.github/workflows/update-changelog.yml
@@ -31,7 +31,7 @@
       - uses: actions/checkout@v1
 
       - name: Generate changelog
-        uses: charmixer/auto-changelog-action@v1
+        uses: charmixer/auto-changelog-action@v1.2
         with:
           token: ${{ secrets.GITHUB_TOKEN }}