filesystems/tahoe-lafs: Update to 1.17.1

Upstream NEWS, omitting bugfixes and minor improvements:

Release 1.17.0 (2021-12-06)
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Security-related Changes
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- The introducer server no longer writes the sensitive introducer fURL value to its log at startup time.  Instead it writes the well-known path of the file from which this value can be read. (`#3819 <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3819>`_)
- The storage protocol operation ``readv`` now safely rejects attempts to read negative lengths.
  Previously these read requests were satisfied with the complete contents of the share file (including trailing metadata) starting from the specified offset. (`#3822 <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3822>`_)
- The storage server implementation no longer records corruption advisories about storage indexes for which it holds no shares. (`#3824 <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3824>`_)
- The lease-checker now uses JSON instead of pickle to serialize its state.

  tahoe will now refuse to run until you either delete all pickle files or
  migrate them using the new command::

      tahoe admin migrate-crawler

  This will migrate all crawler-related pickle files. (`#3825 <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3825>`_)
- The SFTP server no longer accepts password-based credentials for authentication.
  Public/private key-based credentials are now the only supported authentication type.
  This removes plaintext password storage from the SFTP credentials file.
  It also removes a possible timing side-channel vulnerability which might have allowed attackers to discover an account's plaintext password. (`#3827 <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3827>`_)
- The storage server now keeps hashes of lease renew and cancel secrets for immutable share files instead of keeping the original secrets. (`#3839 <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3839>`_)
- The storage server now keeps hashes of lease renew and cancel secrets for mutable share files instead of keeping the original secrets. (`#3841 <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3841>`_)

Features
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- Tahoe-LAFS releases now have just a .tar.gz source release and a (universal) wheel (`#3735 <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3735>`_)
- tahoe-lafs now provides its statistics also in OpenMetrics format (for Prometheus et. al.) at `/statistics?t=openmetrics`. (`#3786 <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3786>`_)
- If uploading an immutable hasn't had a write for 30 minutes, the storage server will abort the upload. (`#3807 <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3807>`_)

Removed Features
----------------

- The little-used "control port" has been removed from all node types. (`#3814 <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3814>`_)

(gdt)