be more strict on niffler versions, add new gz feature to it

[luizirber]

niffler 2.2.0 was released this morning, and now the gz compression is optional too (like bz2 and lzma were before). Because we disable the default features it broke sourmash (because the niffler version was too lax).

This fixes the build errors in #1059

Checklist

• Is it mergeable?
• make test Did it pass the tests?
• make coverage Is the new code covered?
• Did it change the command-line interface? Only additions are allowed
  without a major version increment. Changing file formats also requires a
  major version number increment.
• Was a spellchecker run on the source code and documentation after
  changes were made?

[luizirber]

Ready for review and merge @ctb

[codecov]

Codecov Report

Merging #1070 into master will decrease coverage by 0.55%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1070      +/-   ##
==========================================
- Coverage   83.51%   82.95%   -0.56%     
==========================================
  Files          99       99              
  Lines        8885     8884       -1     
==========================================
- Hits         7420     7370      -50     
- Misses       1465     1514      +49     

Flag	Coverage Δ
#rusttests	68.16% <ø> (ø)

Impacted Files	Coverage Δ
sourmash/_compat.py	52.17% <0.00%> (-47.83%)	⬇️
sourmash/command_compute.py	90.55% <0.00%> (-7.09%)	⬇️
sourmash/sbt_storage.py	88.11% <0.00%> (-4.00%)	⬇️
sourmash/lca/lca_utils.py	92.70% <0.00%> (-3.13%)	⬇️
sourmash/signature.py	89.81% <0.00%> (-2.32%)	⬇️
sourmash/lca/command_gather.py	84.27% <0.00%> (-0.63%)	⬇️
sourmash/lca/command_index.py	89.83% <0.00%> (-0.54%)	⬇️
sourmash/sbt.py	87.32% <0.00%> (-0.28%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 80d975c...2ece50b. Read the comment docs.

[luizirber]

Also bumps the minimum supported Rust version to 1.37, it was coming with #1058 because one of niffler deps (the gz decoder) requires it now 🙄