Don't modify the output the file if the input contents are the same

[richardsondev]

To prevent unnecessary updates to the output file and potential cache invalidation, we can compare the modification times of all input files with that of the output file. If none of the input files have changed, we can skip updating the output file. This approach avoids needless updates that could disrupt caching mechanisms relying on access times.

[richardsondev]

The main challenge here is if a file is deleted. We could look at the directory's modified time?