bpo-45173 Remove configparser deprecations (GH-28292)

In the configparser module, these have been deprecated since Python 3.2:

* the SafeConfigParser class,
* the filename property of the ParsingError class,
* the readfp method of the ConfigParser class,

Doc/library/configparser.rst

@@ -1200,28 +1200,6 @@ ConfigParser Objects
       names is stripped before :meth:`optionxform` is called.
 
 
-   .. method:: readfp(fp, filename=None)
-
-      .. deprecated:: 3.2
-         Use :meth:`read_file` instead.
-
-      .. versionchanged:: 3.2
-         :meth:`readfp` now iterates on *fp* instead of calling ``fp.readline()``.
-
-      For existing code calling :meth:`readfp` with arguments which don't
-      support iteration, the following generator may be used as a wrapper
-      around the file-like object::
-
-         def readline_generator(fp):
-             line = fp.readline()
-             while line:
-                 yield line
-                 line = fp.readline()
-
-      Instead of ``parser.readfp(fp)`` use
-      ``parser.read_file(readline_generator(fp))``.
-
-
 .. data:: MAX_INTERPOLATION_DEPTH
 
    The maximum depth for recursive interpolation for :meth:`get` when the *raw*
@@ -1359,6 +1337,9 @@ Exceptions
       The ``filename`` attribute and :meth:`__init__` argument were renamed to
       ``source`` for consistency.
 
+   .. versionchanged:: 3.11
+      The deprecated ``filename`` attribute was removed.
+
 
 .. rubric:: Footnotes