Switch to hex-publish v3

Author: mworrell

.github/workflows/hex-publish.yml

@@ -13,6 +13,6 @@ jobs:
         uses: actions/checkout@v2
 
       - name: Publish to Hex.pm
-        uses: erlangpack/github-action@v2
+        uses: erlangpack/github-action@v3
         env:
           HEX_API_KEY: ${{ secrets.HEX_API_KEY }}