Set up GitHub Actions for type checking

Author: nsgc

.github/workflows/test.yml .github/workflows/ci.yml.github/workflows/test.yml renamed to .github/workflows/ci.yml

@@ -1,10 +1,10 @@
-name: Test
+name: CI
 
 on:
   push:
 
 jobs:
-  rspec:
+  test:
     runs-on: ubuntu-latest
 
     strategy:
@@ -23,3 +23,17 @@ jobs:
           bundler-cache: true
 
       - run: bundle exec rake test
+
+  steep:
+    name: Type check (Steep)
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: '3.4.4'
+          bundler-cache: true
+
+      - run: bundle exec steep check