Docs: fix typo in doc for sqlite3.Cursor.execute (python#112442)

Author: tom93

Doc/library/sqlite3.rst

@@ -1502,7 +1502,7 @@ Cursor objects
 
    .. method:: execute(sql, parameters=(), /)
 
-      Execute SQL a single SQL statement,
+      Execute a single SQL statement,
       optionally binding Python values using
       :ref:`placeholders <sqlite3-placeholders>`.