Make CI tests dump Docker Compose logs on failure

[jwodder]

So that @dchiquito can figure out why we keep getting intermittent "Digest is missing dandi-etag or sha256 keys." errors.

[codecov]

Codecov Report

Merging #793 (e4aaf27) into master (c9f00c7) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #793   +/-   ##
=======================================
  Coverage   85.07%   85.07%           
=======================================
  Files          59       59           
  Lines        6055     6055           
=======================================
  Hits         5151     5151           
  Misses        904      904           

Flag	Coverage Δ
unittests	85.07% <ø> (ø)

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Impacted Files	Coverage Δ
dandi/tests/fixtures.py	96.37% <0.00%> (-0.73%)	⬇️
dandi/delete.py	91.66% <0.00%> (+0.69%)	⬆️

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[yarikoptic]

ok, lets merge and release in the hope it would come handy ;)