[spine-ts] mesh attachment squashing

aapavlov1994

I use pixi-spine plugin that uses spine-ts lib.
I have a bug with squashing mesh attachments when try to change animation state. it reproduced with

animations made with spine v3.8.99
pixi.js: 6.0.2
pixi-spine: >= 2.1.10

I have found source of the bug and opened PR on git repo.
EsotericSoftware/spine-runtimes1881
It would be grate if you will watch it.

You can see reality and expectation on gifs below.

aapavlov1994

Mario

Thank you for the PR! I've merged it into the 4.0 branch. Sorry for the error, it must have occured during the 4.0 port and not been triggered by our example projects.