Allow .j2 ending on .yml/.yaml files

[oytal]

This PR updates the template file selection regex to support optional .j2 extensions, enabling Jinja syntax highlighting and preventing editor errors when using Jinja variables in compose.yml files.

Old: selectattr('path', 'regex', '.ya?ml$') |
New: selectattr('path', 'regex', '\.ya?ml(\.j2)?$') |

This change allows files like compose.yaml.j2 and compose.yml.j2 to be recognized alongside standard YAML files.

I've tested this change in my own setup and confirmed it does not break existing configurations.

Not sure if this was a problem for anyone else but maybe worth considering merging.

[ironicbadger]

Yo dawg I heard you like to template your templates?

[oytal]

Yo dawg I heard you like to template your templates?

I guess I do?

Example use case is setting a http port in group vars and then reference the same variable in both compose file and in my haproxy config template. Pretty useful in my opinion.