patch 8.2.0079: Python 3 unicode test still fails on MS-Windows

Problem:    Python 3 unicode test still fails on MS-Windows.
Solution:   Do not set 'encoding' to "euc-tw" on MS-Windows.
diff --git a/src/testdir/test_python3.vim b/src/testdir/test_python3.vim
index 4cb5094..aec7721 100644
--- a/src/testdir/test_python3.vim
+++ b/src/testdir/test_python3.vim
@@ -180,10 +180,10 @@
   if !has('win32')
     set encoding=debug
     py3 print('hello')
-  endif
 
-  set encoding=euc-tw
-  py3 print('hello')
+    set encoding=euc-tw
+    py3 print('hello')
+  endif
 
   set encoding=utf8
 endfunc