ci: fix hex authentication in release workflow

Configure hex.config file with API key before publishing to properly
authenticate with hex.pm. The HEX_API_KEY environment variable alone
is not sufficient for rebar3 hex commands.

Author: codeadict

.github/workflows/release.yml

@@ -44,15 +44,20 @@ jobs:
           test -f doc/index.html || (echo "doc/index.html not found" && exit 1)
           echo "Documentation built successfully"
 
-      - name: Publish to Hex
-        run: rebar3 hex publish --yes
+      - name: Configure Hex authentication
+        run: |
+          mkdir -p ~/.config/rebar3
+          cat > ~/.config/rebar3/hex.config <<EOF
+          {api_key, <<"$HEX_API_KEY">>}.
+          EOF
         env:
           HEX_API_KEY: ${{ secrets.HEX_API_KEY }}
 
+      - name: Publish to Hex
+        run: rebar3 hex publish --yes
+
       - name: Publish docs to Hex
         run: rebar3 hex docs publish --yes
-        env:
-          HEX_API_KEY: ${{ secrets.HEX_API_KEY }}
 
       - name: Extract release notes from CHANGELOG
         id: changelog