Build/Test Tools: Remove the dependabot.yml configuration file.
Despite having worked reliably for a few years (first configured in [52241]), the branches and pull requests created by Dependabot are now being deleted and closed after every Git mirror event since early 2024. Since this happens after every commit, the bot is essentially useless in this repository.
This removes the configuration file to avoid unnecessarily creating pull requests and consuming GitHub Actions resources when they will just be closed shortly after.
If the root cause for this change in behavior is discovered and addressed, then re-adding a dependabot.yml file can be considered. For now, you’re just somebody that I used to know.
Props johnbillion, dd32, swissspidy.
Fixes #64140.