test_pipeline should use temporary output directory

[jdbuhler]

test_pipeline runs two scripts that produce output files (bin.yaml and binned_data_local.hdf5). Right now, these files are left in whichever directory the script was run from, which is to say wherever pytest was run. This patch directs them to a temporary directory created by pytest instead so as not to litter the working tree.

[codecov]

Codecov Report

❌ Patch coverage is 66.66667% with 23 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.36%. Comparing base (72e2fb3) to head (e29c194).
⚠️ Report is 12 commits behind head on develop.

Files with missing lines	Patch %	Lines
cosipy/threeml/COSILike.py	66.66%	23 Missing ⚠️

Files with missing lines	Coverage Δ
cosipy/threeml/COSILike.py	73.17% <66.66%> (+3.69%)	⬆️

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[GallegoSav]

Hi @jdbuhler , I see some commits from this pr are coming from your other pull request on the DataIO.

I suppose we need to merge first the pr 457 before this one

[jdbuhler]

Ugh -- I thought I branched from develop. Oh well.