Remove usage of size()

[cmdcolin]

The usage of size() in this library to guard against possibly over-reading the end of the file seems like a unnecessary precaution that results users requiring a more complex CORS config e.g. exposing content-range which seems somewhat atypical for CORS configs

I think that size() is precautionary and anything that fetched past the end of the file would imply a corrupt index so our code wouldn't really help the fact that the index is corrupt and therefore, can probably be removed

[codecov]

Codecov Report

Merging #99 into master will decrease coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #99      +/-   ##
==========================================
- Coverage   90.79%   90.74%   -0.06%     
==========================================
  Files           7        7              
  Lines         554      551       -3     
  Branches      150      149       -1     
==========================================
- Hits          503      500       -3     
  Misses         51       51              

Impacted Files	Coverage Δ
src/tabixIndexedFile.ts	91.47% <ø> (-0.15%)	⬇️

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