Add required dependencies and install them before running verification

This fixes #65.

Author: tillrohrmann

.github/workflows/pre-release.yml

@@ -85,7 +85,9 @@ jobs:
       # examples workspace, so we test them separately here.
       - name: Test kotlin/hello-world-lambda-cdk
         if: github.event.inputs.sdkTypescriptVersion != '' && github.event.inputs.sdkJavaVersion != ''
-        run: npm --prefix kotlin/hello-world-lambda-cdk run verify
+        run: |
+          npm --prefix kotlin/hello-world-lambda-cdk install
+          npm --prefix kotlin/hello-world-lambda-cdk run verify
 
       - name: Create Pull Request
         uses: peter-evans/create-pull-request@v5