Feature request: Support for file triggers

I am using nfpm (which is based on rpmpack) to build some rpms. I would like to add file triggers, but rpmpack does not support them yet.

It looks like these are the relevant tags, sorted by tag number:

| Tag Name | Value | Type |
|------------------------|-------|--------------|
| Filetriggerscripts | 5066 | string array |
| Filetriggerscriptprog | 5067 | string array |
| Filetriggerscriptflags | 5068 | int32 array |
| Filetriggername | 5069 | string array |
| Filetriggerindex | 5070 | int32 array |
| Filetriggerversion | 5071 | string array |
| Filetriggerflags | 5072 | int32 array |
| Filetriggerpriorities | 5084 | int32 array |

Relevant docs:
https://rpm-software-management.github.io/rpm/manual/tags.html#file-triggers
https://rpm-software-management.github.io/rpm/manual/file_triggers.html

Background:
My rpm contains a python virtualenv (or more precisely, it has a PEX file that `%post` uses to generate a venv). I would like to have a file trigger for `/usr/bin/python3.10` (or similar) so I can recreate the venv when the interpreter gets upgraded.