fix: bump up the default jest timeout in the UI tests (#768)

Hopefully this will give some breathing room to our current UI tests
that are right on the cusp of the default 5000ms timeout. This won't
catch all of our flaky tests, but hopefully will address the ones that
are caused by timeouts. Closes #615

@german-mergestat what do you think?

ui/jest.config.js

@@ -2,6 +2,7 @@ const nextJest = require('next/jest')
 
 const createJestConfig = nextJest({
   dir: './',
+  testTimeout: 20000,
 })
 
 const customJestConfig = {