patch 9.1.0336: tests: typo in test_xdg

Problem:  tests: typo in test_xdg
Solution: fix typo (Diego Viola)

closes: #14562

Signed-off-by: Diego Viola <diego.viola@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_xdg.vim b/src/testdir/test_xdg.vim
index b24205b..d23c93a 100644
--- a/src/testdir/test_xdg.vim
+++ b/src/testdir/test_xdg.vim
@@ -54,7 +54,7 @@
   let rc4=expand('~/xdg/vim/vimrc')
 
   " g:rc_one|two|three|four is to verify, that the other
-  " init files are not source
+  " init files are not sourced
   " g:rc is to verify which rc file has been loaded.
   let file1 =<< trim CODE
     let g:rc_one = 'one'