Fix workflow

Author: sue445

.github/workflows/build.yml

@@ -19,6 +19,7 @@ on:
 env:
   TEST_ARGS: -coverprofile coverage.out -covermode atomic
   TEST_GEM_DIR: ruby/testdata/example/
+  GO_GEM_DIR: gem/
 
 jobs:
   test:
@@ -158,12 +159,45 @@ jobs:
           status: ${{ job.status }}
           webhook-url: ${{ secrets.SLACK_WEBHOOK }}
 
+  go_gem:
+    name: "go_gem (Ruby ${{ matrix.ruby }})"
+
+    runs-on: ubuntu-latest
+
+    strategy:
+      fail-fast: false
+
+      matrix:
+        ruby:
+          - "3.3"
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+
+      - run: bundle exec rspec
+        working-directory: ${{ env.GO_GEM_DIR }}
+
+      - name: Slack Notification (not success)
+        uses: act10ns/slack@v2
+        if: "! success()"
+        continue-on-error: true
+        with:
+          status: ${{ job.status }}
+          webhook-url: ${{ secrets.SLACK_WEBHOOK }}
+          matrix: ${{ toJson(matrix) }}
+
   notify:
     needs:
       - test
       - go-lint
       - ruby-lint
       - ruby-rbs
+      - go_gem
 
     runs-on: ubuntu-latest