runtime(openPlugin): fix unclosed parenthesis in GetWordUnderCursor()

Problem:

Saw the following error when invoking gx mapping with cursor on a URL:

    Error detected while compiling function <SNR>95_GetWordUnderCursor:
    line    7:
    E1123: Missing comma before argument: return expand(user_var)
    E116: Invalid arguments for function dist#vim9#Open

Solution:

The line before "return expand(...)" has two open parentheses but only
one close parenthesis. Add another close parenthesis.

closes: #16553

Signed-off-by: Morton Fox <github@qslw.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/runtime/plugin/openPlugin.vim b/runtime/plugin/openPlugin.vim
index c231dc4..51592f0 100644
--- a/runtime/plugin/openPlugin.vim
+++ b/runtime/plugin/openPlugin.vim
@@ -3,7 +3,7 @@
 # Vim runtime support library
 #
 # Maintainer:   The Vim Project <https://github.com/vim/vim>
-# Last Change:  2025 Jan 24
+# Last Change:  2025 Feb 01
 
 import autoload 'dist/vim9.vim'
 
@@ -18,7 +18,7 @@
       return url
     endif
 
-    const user_var = get(g:, 'gx_word', get(g:, 'netrw_gx', '<cfile>')
+    const user_var = get(g:, 'gx_word', get(g:, 'netrw_gx', '<cfile>'))
     return expand(user_var)
   enddef