chore: publish to hex.pm workflow (#15)

Author: Ziinc

.github/workflows/publish.yaml

@@ -0,0 +1,25 @@
+name: Publish Elixir package
+
+on:
+  workflow_dispatch:
+
+jobs:
+  publish:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: erlef/setup-beam@v1
+        with:
+          version-file: .tool-versions
+          version-type: strict
+      - name: Restore dependencies cache
+        uses: actions/cache@v3
+        with:
+          path: deps
+          key: ${{ runner.os }}-mix-${{ hashFiles('**/mix.lock') }}
+          restore-keys: ${{ runner.os }}-mix-
+      - run: mix deps.get
+      - run: mix hex.publish --yes
+        if: github.event_name == 'workflow_dispatch'
+        env:
+          HEX_API_KEY: ${{ secrets.HEX_AUTH_TOKEN }}