Add a .gitattributes

[williamdes]

This will lower the bundle size to only 3 files

$ du -sh /home/williamdes/array-diff-multidimensional-master
188K	/home/williamdes/array-diff-multidimensional-master
$ du -sh /home/williamdes/array-diff-multidimensional-gitattrs
44K	/home/williamdes/array-diff-multidimensional-gitattrs
$ du -sh /home/williamdes/array-diff-multidimensional-master/*
12K	/home/williamdes/array-diff-multidimensional-master/composer.json
12K	/home/williamdes/array-diff-multidimensional-master/phpunit.xml
12K	/home/williamdes/array-diff-multidimensional-master/README.md
16K	/home/williamdes/array-diff-multidimensional-master/src
24K	/home/williamdes/array-diff-multidimensional-master/tests
$ du -sh /home/williamdes/array-diff-multidimensional-gitattrs/*
12K	/home/williamdes/array-diff-multidimensional-gitattrs/composer.json
12K	/home/williamdes/array-diff-multidimensional-gitattrs/README.md
16K	/home/williamdes/array-diff-multidimensional-gitattrs/src

git archive HEAD --format zip --output=repo.zip

[sonarqubecloud]

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[rogervila]

Hi @williamdes, thank you for your contribution!
I will merge once the CI tests pass.