Add application/zstd as a MIME type for zstandard compression

[codecov[bot]]

Codecov Report

Merging #13 into master will decrease coverage by 0.83%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #13      +/-   ##
==========================================
- Coverage   92.44%   91.61%   -0.84%     
==========================================
  Files          14       13       -1     
  Lines         556      453     -103     
==========================================
- Hits          514      415      -99     
+ Misses         42       38       -4     

Impacted Files	Coverage Δ
destream/decompressors/zstd.py	100.00% <100.00%> (ø)
destream/decompressors/rar.py

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[cecton]

@jruere I uploaded the v5.0.1 with this fix. Thank you for your contribution

[jruere]

Thank you!