Bump version to 5.3.4 and update cache-bust params

[xirvik]

Bug fixes since v5.3.3.

Ratio plugin

• Gate the group.*.ratio.*.set call shape by rtorrent version so the ratio
  plugin works on rtorrent 0.15.x as well as 0.16.x. 0.16 strictly requires
  (target, value) while 0.15.x strictly requires the bare value; the
  adaptation now lives in rTorrentSettings::getRatioGroupCommand and is chosen
  by iVersion. Also drops the group2.* prefix path (stubbed on 0.15.x,
  removed in 0.16) and the now-unused $ratioCmds whitelist.
  (@xirvik, Ratio plugin: gate group.*.set call shape by rtorrent version #3071 — fixes the 0.15.x regression reported by @ml-1 in After installing 5.3.2, the ratio plugin stop working. #3065)

erasedata / httprpc

• "Remove and delete data" now records the file list over RPC using canonical
  commands (d.base_path, d.is_multi_file, f.multicall/f.frozen_path)
  and writes the erasedata .list file directly, instead of relying on the
  file.append erase event. Stock rtorrent 0.16.x does not register
  file.append (it's gated behind method.use_deprecated, which the rc can no
  longer enable in time), so the torrent was removed but its data silently
  orphaned. The new path works on every rtorrent version.
  (@xirvik, httprpc/erasedata: capture delete-with-data file list over RPC #3073)