Run gentype tests in CI (#6468)

Author: cknitt

.github/workflows/ci.yml

@@ -210,6 +210,10 @@ jobs:
         if: runner.os != 'Windows'
         run: node scripts/ciTest.js -all
 
+      - name: Run gentype tests
+        if: runner.os != 'Windows'
+        run: make -C jscomp/gentype_tests/typescript-react-example clean test
+
       - name: Run tests (Windows)
         if: runner.os == 'Windows'
         run: node scripts/ciTest.js -mocha -theme -format