Update .gitattributes

[KarelWintersky]

Description

We exclude these files because they are not required for the package to function properly in a production environment

Motivation and context

Less useless files

How has this been tested?

no tests required

Types of changes

What types of changes does your code introduce? Put an x in all the boxes that apply:

• Bug fix (non-breaking change which fixes an issue)
• [] New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

Go over all the following points, and put an x in all the boxes that apply.

Please, please, please, don't send your pull request until all of the boxes are ticked. Once your pull request is created, it will trigger a build on our continuous integration server to make sure your tests and code style pass.

• I have read the CONTRIBUTING document.
• My pull request addresses exactly one patch/feature.
• I have created a branch for this patch/feature.
• Each individual commit in the pull request is meaningful.
• I have added tests to cover my changes.
• If my change adds a new code file, I have added the copyright header to it.
• If my change requires a change to the documentation, I have updated it accordingly.

If you're unsure about any of these, don't hesitate to ask. We're here to help!

[colinodell]

Thanks for the PR!

[KarelWintersky]

When will you release a new release version for packagist?

[KarelWintersky]

When will you release a new release version for packagist?