diffoscope: upgrade 293 -> 297

diffoscope: upgrade 293 -> 297

Also, remove the musl restriction - it builds successfully with both glibc and musl.

Changelog:
294:
- Correct longstanding issue where many ">"-based version tests used in
  conditional fixtures were broken due to the lack of a __gt__ method.
  Thanks, Colin Watson! (Closes: #1102658)
- Address a long-hidden issue in the test_versions testsuite where we weren't
  actually testing ">" as it was masked by the tests for equality in the
  testsuite.
- Update copyright years.

295:
- Use --walk over the potentially dangerous --scan argument of zipdetails(1).
  (Closes: reproducible-builds/diffoscope#406)

296:
- Don't rely on zipdetails' --walk functionality to be available; only add
  that argument after testing for a new enough versions.
  (Closes: reproducible-builds/diffoscope#408)
- Disable and then re-enable failing on stable-bpo.
- Update copyright years.
- Add NuGet package support.

297:
- Add a LZMA comparator and tests.

Signed-off-by: Gyorgy Sarvari <skandigraun@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>