Usage of とwhere it seems てshould be used


I recently started playing _Pokémon: Let's Go, Eevee!_ in Japanese, and I have
seen this grammar come up a few times. Most recently in the following dialog.

> この ポケモンジムは **閉まっとる**

To me it seems as if the て was replaced with と, as in 「閉まっ **て** る」.

When I first came across this I tried looking up this structure, but to no
avail. I couldn't seem to find anything on this type of grammar. Then I
thought I may have just caught a typo and moved on. But after seeing the same
structure pop up a few times I realized it must be something I haven't seen
before.

I still cannot seem to find anything on this structure (maybe my googling
skills just aren't up to snuff). Is this some verb form that I have yet to
learn? Is it the と particle in an unfamiliar position? Or possibly some kind
of dialect they're using?

