misc: build a service client during release checks (#1152)

Author: lauzadis

.github/workflows/update-release-branch.yml

@@ -71,6 +71,14 @@ jobs:
           # This should help prevent the cases where we forgot to bump smithy-kotlin versions and don't catch it
           # because CI is masking it
           ./gradlew -Paws.kotlin.native=false test jvmTest
+      - name: Release Check - build an SDK client
+        if: env.MERGED_NEEDED == 'true'
+        shell: bash
+        run: |
+          # Additionally generate and build a service client to confirm that codegen and build works
+          # without "live at HEAD" mode.
+          ./gradlew -Paws.services=s3 -Paws.kotlin.native=false bootstrap; 
+          ./gradlew -Paws.kotlin.native=false build;
       - name: Merge
         if: env.MERGE_NEEDED == 'true'
         shell: bash