Log Message:
filesystems/tahoe-lafs: Update to 1.18.0

packaging changes: Drop explanation about python 2.7 being supported
by upstream and $MAINTAINER not wanting to deal with dependencies.

Upstream NEWS:

Release 1.18.0 (2022-10-02)
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Backwards Incompatible Changes
------------------------------

- Python 3.6 is no longer supported, as it has reached end-of-life and is no \ 
longer receiving security updates. (`#3865 \ 
<https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3865>`_)
- Python 3.7 or later is now required; Python 2 is no longer supported. (`#3873 \ 
<https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3873>`_)
- Share corruption reports stored on disk are now always encoded in UTF-8. \ 
(`#3879 <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3879>`_)
- Record both the PID and the process creation-time:

  a new kind of pidfile in `running.process` records both
  the PID and the creation-time of the process. This facilitates
  automatic discovery of a "stale" pidfile that points to a
  currently-running process. If the recorded creation-time matches
  the creation-time of the running process, then it is a still-running
  `tahoe run` process. Otherwise, the file is stale.

  The `twistd.pid` file is no longer present. (`#3926 \ 
<https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3926>`_)

Features
--------

- The implementation of SDMF and MDMF (mutables) now requires RSA keys to be \ 
exactly 2048 bits, aligning them with the specification.

  Some code existed to allow tests to shorten this and it's
  conceptually possible a modified client produced mutables
  with different key-sizes. However, the spec says that they
  must be 2048 bits. If you happen to have a capability with
  a key-size different from 2048 you may use 1.17.1 or earlier
  to read the content. (`#3828 \ 
<https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3828>`_)
- "make" based release automation (`#3846 \ 
<https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3846>`_)