Add crates.io publishing workflow

Author: tenderlove

.github/workflows/publish-crate.yml

@@ -0,0 +1,32 @@
+name: Publish to crates.io
+on:
+  push:
+    tags: ['v*']  # Triggers when pushing tags starting with 'v'
+jobs:
+  publish:
+    if: github.repository == 'ruby/prism'
+    runs-on: ubuntu-latest
+    environment: release  # Optional: for enhanced security
+    permissions:
+      id-token: write     # Required for OIDC token exchange
+    steps:
+      - name: Harden Runner
+        uses: step-security/harden-runner@f4a75cfd619ee5ce8d5b864b0d183aff3c69b55a # v2.13.1
+        with:
+          egress-policy: audit
+      - uses: actions/checkout@v5
+
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@eaecf785f6a34567a6d97f686bbb7bccc1ac1e5c # v1.237.0
+        with:
+          ruby-version: ${{ matrix.ruby }}
+
+      - name: Install dependencies
+        run: bundle install --jobs 4 --retry 3
+
+      - uses: rust-lang/crates-io-auth-action@v1
+        id: auth
+
+      - run: bundle exec rake cargo:publish:real
+        env:
+          CARGO_REGISTRY_TOKEN: ${{ steps.auth.outputs.token }}