Add data file to dependency file

[everlanes]

When using a data attribute for loading external data from a file, this data file is added to the dependency file. Changing the content of the data file now triggers a rebuild of the pages and posts which are including it.

Signed-off-by: Andreas Brinner andreas@everlanes.net

Pull Request Checklist

• [x] I’ve read the guidelines for contributing.
• [x] I updated AUTHORS.txt and CHANGES.txt (if the change is non-trivial) and documentation (if applicable).
• [x] I tested my changes.

Description

I tested with my own site and confirmed that the dependencies were added correctly.

[Kwpolska]

Thanks for contributing this fix!