Stretch goal: Optimize pmtiles creation triggering

[jcpitre]

In #913 (comment) we proposed a possible optimisation:

When calling the function with a dataset, also provide the previous latest dataset for the given feed. We could then check if the unzipped files of interest (stops.txt, shapes.txt, etc) have changed and regenerate the pmtiles only in case of a change.

[jcpitre]

This was done as part of #1011. In that case we check if the gtfs files have changed (different hash) before sending the message to create the pmtiles.

[cka-y]

This was covered as part of #1290 and used in #1011. I think we can close this one as completed cc @emmambd

[emmambd]

@cka-y Then what issue best reflects the outstanding work discussed this morning?

[cka-y]

I think it would be #1311 which is already added to the board