Fix "encodings" typo in argparse.FileType documentation (GH-148502)

(cherry picked from commit 8ecb6b8)

Co-authored-by: Gleb Popov <gvpopov.dev@gmail.com>

Author: gleb-pp

Doc/library/argparse.rst

@@ -1934,7 +1934,7 @@ FileType objects
       run and then use the :keyword:`with`-statement to manage the files.
 
    .. versionchanged:: 3.4
-      Added the *encodings* and *errors* parameters.
+      Added the *encoding* and *errors* parameters.
 
    .. deprecated:: 3.14