feat: infer additional statistics from read lengths

[balajtimate]

Description

• Rewrite get_library_stats.py to infer mean, median and mode from the sample read length
• Add additional adapter fragment sequence
• Refactor htsinfer.py so the results print to STDOUT is now sorted in order of inference (instead of alphabetical)
• Update logging messages and README.md
• Downgrade Kallisto version as it was causing issues with CI

Fixes #132

Type of change

• New feature (non-breaking change which adds functionality)

Checklist

• I have performed a self-review of my own code
• My code follows the existing coding style, lints and generates no new
  warnings
• I have added type annotations to all function/method signatures, and I
  have added type annotations for any local variables that are non-trivial,
  potentially ambiguous or might otherwise benefit from explicit typing.
• I have commented my code in hard-to-understand areas
• I have added ["Google-style docstrings"] to all new modules, classes,
  methods/functions or updated previously existing ones
• I have added tests that prove my fix is effective or that my feature
  works
• New and existing unit tests pass locally with my changes and I have not
  reduced the code coverage relative to the previous state
• I have updated any sections of the app's documentation that are affected
  by the proposed changes

[codecov]

Codecov Report

Patch coverage: 100.00% and no project coverage change.

Comparison is base (d6d892c) 99.80% compared to head (6774063) 99.80%.

Additional details and impacted files

@@           Coverage Diff           @@
##              dev     #133   +/-   ##
=======================================
  Coverage   99.80%   99.80%           
=======================================
  Files          12       12           
  Lines        1024     1039   +15     
=======================================
+ Hits         1022     1037   +15     
  Misses          2        2           

Files Changed	Coverage Δ
htsinfer/htsinfer.py	100.00% <ø> (ø)
htsinfer/get_library_stats.py	100.00% <100.00%> (ø)
htsinfer/models.py	100.00% <100.00%> (ø)

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