Yarn upgrade

[zachmullen]

I isolated the two package upgrades that were causing test failures. Luckily both of them are test-time only packages:

• @vue/test-utils (which is still in beta, so it's understandable)
• axios-mock-adapter

I've fixed those two and upgraded the rest of the packages. I'll follow this up with a PR to migrate to the newer versions of the above packages.