Fix bz2 unzip function errors

[simonrp84]

The bz2 unzip function in readers/utils.py doesn't close the BZ2 file handler, which on some platforms leads to permission errors when os.remove tries to delete the unclosed files. This PR wraps the BZ2 handler in a with closing() statement to prevent this error.

[mraspaud]

Maybe related to this https://github.com/pytroll/satpy/issues/2183 ?

[codecov[bot]]

Codecov Report

Merging #2193 (4f01ae7) into main (0c2b965) will decrease coverage by 0.00%. The diff coverage is 85.96%.

@@            Coverage Diff             @@
##             main    #2193      +/-   ##
==========================================
- Coverage   94.19%   94.19%   -0.01%     
==========================================
  Files         295      295              
  Lines       45393    45396       +3     
==========================================
+ Hits        42760    42761       +1     
- Misses       2633     2635       +2     

Flag	Coverage Δ
behaviourtests	4.66% <0.00%> (-0.01%)	:arrow_down:
unittests	94.84% <85.96%> (-0.01%)	:arrow_down:

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

Impacted Files	Coverage Δ
satpy/readers/utils.py	91.95% <45.45%> (ø)
satpy/tests/reader_tests/test_utils.py	99.25% <95.65%> (-0.75%)	:arrow_down:

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[coveralls]

Coverage decreased (-0.004%) to 94.792% when pulling 4f01ae7cfdf8f3c5b1d3ecda5df8a00a1f1e8dee on simonrp84:fix_bz2_unzip into 0c2b9650e48867fbfb6292102400e3d5007bf74a on pytroll:main.

[mraspaud]

Looks good, do you think the block above could also drop the closing or would the raising in the except block be a problem?

[simonrp84]

@mraspaud I think it should be OK to remove that closing but that's not my code originally so I'm not 100% sure what the original purpose was. I'll remove it as the tests pass OK for this.

[mraspaud]

I think there has been quite some work merged for this already, so I'm closing this PR for now. Feel free to reopen if it turns out that problem isn't solved.