[3.12] pythongh-126259: Fix "unclosed database" warning in sqlite3 do…

…ctest (pythonGH-126260) (python#126266)

(cherry picked from commit 295262c)

Co-authored-by: sobolevn <[email protected]>

Doc/library/sqlite3.rst

@@ -2420,6 +2420,7 @@ Some useful URI tricks include:
    >>> con.execute("CREATE TABLE readonly(data)")
    Traceback (most recent call last):
    OperationalError: attempt to write a readonly database
+   >>> con.close()
 
 * Do not implicitly create a new database file if it does not already exist;
   will raise :exc:`~sqlite3.OperationalError` if unable to create a new file: