MRG: run rust checks always

[ctb]

Fixes #2550

There were some concerns about how long things take to run, so we'll evaluate that and maybe revert this change if it slows down PRs.

Alternatively, we could implement #2342 and make better use of draft PRs.

[codecov]

Codecov Report

Merging #2787 (fbaeb8a) into latest (c2d1d15) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           latest    #2787   +/-   ##
=======================================
  Coverage   85.94%   85.94%           
=======================================
  Files         130      130           
  Lines       14808    14808           
  Branches     2621     2621           
=======================================
  Hits        12727    12727           
  Misses       1780     1780           
  Partials      301      301           

Flag	Coverage Δ
hypothesis-py	25.82% <ø> (ø)
python	92.85% <ø> (ø)
rust	49.93% <ø> (ø)

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[ctb]

The longest rust checks take 22m.

I'd say, let's merge this, and we can refactor to just run on final PRs if it becomes a problem.

@sourmash-bio/devs ready for review!

[bluegenes]

22 min is pretty long, but the try-then-refactor approach sounds good to me