Only validate loom version when mixins are to be remapped with TinyRemapper

[mezz]

I think there is an inversion in the logic introduced in #980

The comments for MixinRemapType.STATIC say "Jar does not use refmaps, so will be remapped by tiny-remapper"
And the comments for validateLoomVersion say "This is only done for jars with tiny-remapper remapped mixins."

So I think the logic should be checking == STATIC instead of != STATIC

[mezz]

I was able to add new failing tests, and confirm that now they pass with the PR changes

I also had to change two tests in order to match the new code changes,
"Invalid loom version" and "Valid loom version"
used to check for remap type "mixin" and now they test for type "static"