ENH: Add support for BrotliDecode filter (PDF 2.0) #3223

[ash01ish]

Implements the BrotliDecode filter as specified in ISO 32000-2:2020, Section 7.4.11. Adds necessary constants, integrates the filter into the decoding logic, includes brotli as an optional dependency, adds unit tests, and updates documentation.

Closes #3223

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.60%. Comparing base (b185ab3) to head (00e124c).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3254   +/-   ##
=======================================
  Coverage   96.60%   96.60%           
=======================================
  Files          53       53           
  Lines        8973     8992   +19     
  Branches     1659     1662    +3     
=======================================
+ Hits         8668     8687   +19     
  Misses        183      183           
  Partials      122      122           

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[stefan6419846]

Thanks for the PR. Is the official specification available in the meantime?

Apart from this, I have left some comments I stumbled upon during the review.

[ash01ish]

Reverting the requirements.txt files to main will show an error that the package is not installed. Is there any other way to get them installed? - I have added them in dev.in and ci.in - expecting that the req will be generated while running the pipeline.

[ash01ish]

Is the official specification available in the meantime?

The official specification for Brotli compression in PDF is not yet released. However, the PDF Association has announced its upcoming inclusion in PDF 2.0. Sample PDF files are available for developers to begin testing. https://pdfa.org/brotli-compression-coming-to-pdf/

[stefan6419846]

Reverting the requirements.txt files to main will show an error that the package is not installed. Is there any other way to get them installed? - I have added them in dev.in and ci.in - expecting that the req will be generated while running the pipeline.

You can change the .txt variants, but ONLY for the actual dependency.

[stefan6419846]

Do we really need this as local imports?