Auto-label PRs

[witzki]

This PR closes partly Issue #2095.
It adds labels when changing data, as described in the issue. But it does not add labels to words in the PR title. Therefore an issue and a pull request from others is already open in actions/labeler.
actions/labeler#109
actions/labeler#55

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Thank you for submitting a Pull Request to the Mobile Security Testing Guide. Please make sure that:

• Your contribution is written in the 2nd person (e.g. you)
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If your PR is related to an issue. Please end your PR test with the following line:
This PR closes #< insert number here >.

[cpholguera]

Thanks a lot @witzki!