…n size > 1MB (genintho)

This PR was squashed before being merged into the 3.4.x-dev branch.

Discussion
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API DOC https://docs.github.com/en/rest/repos/contents

The API call to return the content of a file return an empty content if a file is bigger than 1MB. 
To be able to download that file, we need to provide the header `application/vnd.github.VERSION.raw`. 
When doing so, the API return a the raw file, instead of a JSON object with some attributes + the file content. 

Because the API has a different behavior, I preferred to create a dedicated method as opposed to provide accept more option in the download method and having a bunch of if/else.


Note: a 3rd behavior exists for that API call when downloading markdown and passing the `application/vnd.github.VERSION.html` header, which is not supported by this code change.

Commits
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520ffb9 Add the ability to download raw file, needed when size > 1MB
ff458a2 Restore modification committed by mistake
e7c393f Style fix

…viewRequest` (rob006)

This PR was squashed before being merged into the 3.9.x-dev branch.

Discussion
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Commits
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628a749 PHPDoc: fix return type in `Assignees::remove()`
3d40ebb PHPDoc: fix return type in `Assignees::add()`
a8747ac PHPDoc: fix return type in `ReviewRequest::remove()`