Fix HelloWorld CI following update to v4.0 (#3997)

Author: thomas-bc

.github/workflows/ext-build-hello-world.yml

@@ -31,6 +31,7 @@ jobs:
     uses: ./.github/workflows/reusable-project-builder.yml
     with:
       target_repository: fprime-community/fprime-tutorial-hello-world
+      fprime_location: ./lib/fprime
       build_location: HelloWorldDeployment
       run_unit_tests: false # no UTs in HelloWorld project
       target_ref: ${{ needs.get-branch.outputs.target-branch }}