Add refresh step to entrypoint test

Author: zooba

.github/workflows/build.yml

@@ -174,6 +174,8 @@ jobs:
 
     - name: 'Validate entrypoint script'
       run: |
+        del pip* -Verbose
+        pymanager install --refresh
         dir pip*
         Get-Item .\pip.exe
         Get-Item .\pip.exe.__target__