patch 8.2.4020: debugger test fails

Problem:    Debugger test fails.
Solution:   Fix import statement.
diff --git a/src/testdir/test_debugger.vim b/src/testdir/test_debugger.vim
index 659c7a8..0c4bc87 100644
--- a/src/testdir/test_debugger.vim
+++ b/src/testdir/test_debugger.vim
@@ -891,7 +891,7 @@
   CheckCWD
   let file1 =<< trim END
     vim9script
-    import File2Function from './Xtest2.vim'
+    import './Xtest2.vim' as imp
 
     def SourceAnotherFile()
       source Xtest2.vim
@@ -899,7 +899,7 @@
 
     def CallAFunction()
       SourceAnotherFile()
-      File2Function()
+      imp.File2Function()
     enddef
 
     def g:GlobalFunction()