Run build:systemjs using pnpm (no nx)

Author: alexslavr

.github/workflows/qunit_tests-additional-renovation.yml

@@ -62,7 +62,7 @@ jobs:
         run: |
           node ../../tools/scripts/performance_log.js &
           pnpx nx build:dev
-          pnpx nx build:systemjs
+          pnpm run build:systemjs
 
       - name: Zip artifacts
         working-directory: ./packages/devextreme