add github action to cross compile gems

.github/workflows/ruby-cross-compile.yml

@@ -0,0 +1,62 @@
+---
+name: Build Ruby gems
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  ci-data:
+    runs-on: ubuntu-latest
+    outputs:
+      result: ${{ steps.fetch.outputs.result }}
+    steps:
+      # This compiles for all supported Ruby cross-compilation platforms.
+      - id: fetch
+        uses: oxidize-rb/actions/fetch-ci-data@main
+        with:
+           supported-ruby-platforms: |
+            exclude: []
+          stable-ruby-versions: |
+            exclude: [head]
+
+  cross_gems:
+    name: Cross compile gems
+    needs: ci-data
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        ruby-platform: ${{ fromJSON(needs.ci-data.outputs.result).supported-ruby-platforms }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: oxidize-rb/actions/setup-ruby-and-rust@v1
+        with:
+          ruby-version: "3.3"
+          bundler-cache: true
+          cargo-cache: true
+          cargo-vendor: true
+          cache-version: v2-${{ matrix.ruby-platform }}
+
+      - name: Set vars
+        id: vars
+        run: |
+          echo "rb-sys-version=$(bundle exec ruby -rrb_sys -e 'puts RbSys::VERSION')" >> $GITHUB_OUTPUT
+
+      - uses: "ruby/setup-ruby@v1"
+        with:
+          ruby-version: "3.2"
+          bundler-cache: true
+
+      - uses: oxidize-rb/cross-gem-action@main
+        with:
+          version: ${{ steps.vars.outputs.rb-sys-version }}
+          platform: ${{ matrix.ruby-platform }}
+          ruby-versions: ${{ join(fromJSON(needs.ci-data.outputs.result).stable-ruby-versions, ', ') }}