[MRG] pin setuptools < 60

[ctb]

When testing out sourmash v4.3.0 rc1, I ran into an error linking to libthread on farm, and when I revisited #1772, I saw a new reverse link from this issue:

sherpa/sherpa#1456

which recommended that we downgrade setuptools to <60. I tested it on farm, and that indeed allowed the build to proceed.

I'm going to merge this when tests pass, so I can cut the release.

[codecov]

Codecov Report

Merging #1879 (6e653b2) into latest (f3ae570) will increase coverage by 7.93%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           latest    #1879      +/-   ##
==========================================
+ Coverage   82.61%   90.55%   +7.93%     
==========================================
  Files         121       91      -30     
  Lines       13105     8903    -4202     
  Branches     1756     1756              
==========================================
- Hits        10827     8062    -2765     
+ Misses       2015      578    -1437     
  Partials      263      263              

Flag	Coverage Δ
python	90.55% <ø> (ø)
rust	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/core/src/encodings.rs
src/core/src/ffi/nodegraph.rs
src/core/src/ffi/mod.rs
src/core/src/ffi/utils.rs
src/core/src/ffi/index/mod.rs
src/core/src/sketch/hyperloglog/mod.rs
src/core/src/ffi/cmd/compute.rs
src/core/src/lib.rs
src/core/src/storage.rs
src/core/src/ffi/index/revindex.rs
... and 20 more

---

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 f3ae570...6e653b2. Read the comment docs.