build: fix UniverseLib build script

Author: Scoolnik

.github/workflows/dotnet_nightly.yml

@@ -42,7 +42,8 @@ jobs:
 
       - if: ${{ steps.cache-universe-lib-build.outputs.cache-hit != 'true' }}
         name: Build UniverseLib
-        run: ./UniverseLib/build.ps1
+        working-directory: ./UniverseLib
+        run: ./build.ps1
 
       - name: Build UE
         run: ./build_nightly.ps1