Remove pyarrow as hard dep

[yannikschaelte]

No description provided.

[codecov-commenter]

Codecov Report

Merging #523 (0fae14f) into develop (ae48c18) will increase coverage by 0.04%.
The diff coverage is 55.55%.

❗ Current head 0fae14f differs from pull request most recent head e5c4c39. Consider uploading reports for the commit e5c4c39 to get more accurate results

@@             Coverage Diff             @@
##           develop     #523      +/-   ##
===========================================
+ Coverage    88.59%   88.64%   +0.04%     
===========================================
  Files          125      125              
  Lines         7421     7425       +4     
===========================================
+ Hits          6575     6582       +7     
+ Misses         846      843       -3     

Impacted Files	Coverage Δ
pyabc/storage/dataframe_bytes_storage.py	85.13% <55.55%> (+5.13%)	⬆️
pyabc/inference_util.py	95.89% <0.00%> (-0.69%)	⬇️
pyabc/weighted_statistics.py	92.06% <0.00%> (ø)
pyabc/sampler/mapping.py	97.50% <0.00%> (+2.50%)	⬆️

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