package/python3: security bump to version 3.9.4

package/python3: security bump to version 3.9.4

Fixes the following security issues:

- bpo-42988: CVE-2021-3426: Remove the getfile feature of the pydoc module
  which could be abused to read arbitrary files on the disk (directory
  traversal vulnerability).  Moreover, even source code of Python modules
  can contain sensitive data like passwords.  Vulnerability reported by
  David Schwörer.

- bpo-43285: ftplib no longer trusts the IP address value returned from the
  server in response to the PASV command by default.  This prevents a
  malicious FTP server from using the response to probe IPv4 address and
  port combinations on the client network.

  Code that requires the former vulnerable behavior may set a
  trust_server_pasv_ipv4_address attribute on their ftplib.FTP instances to
  True to re-enable it.

- bpo-43439: Add audit hooks for gc.get_objects(), gc.get_referrers() and
  gc.get_referents().  Patch by Pablo Galindo.

Note: 3.9.3 was recalled due to introducing unintentional ABI
incompatibility, and fixes re-released as 3.9.4:

https://www.python.org/downloads/release/python-394/

Add host-autoreconf-archive, as it is needed for autoreconf since:
https://github.com/python/cpython/commit/064bc07f241dceec2fc577cbf5c31fa6d63fe320

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>