fix: rollup errors

[just-toby]

for some reason, changing these consts to regular function syntax fixes the rollup errors that we've been seeing (in the terminal when running yarn start)

example of the error:

rollup building...
Error when using sourcemap for reporting an error: Can't resolve original location of error.
{
  column: 13,
  file: '/Users/eddie.dugan/Documents/widgets/src/components/Swap/Toolbar/Caption.tsx',
  line: 4
} 

The 'this' keyword is equivalent to 'undefined' at the top level of an ES module, and has been rewritten
{
  column: 13,
  file: '/Users/eddie.dugan/Documents/widgets/src/components/Swap/Toolbar/Caption.tsx',
  line: 4
} 

to verify that this actually fixes the errors like I claim, checkout this branch and run yarn && yarn start

[vercel]

The latest updates on your projects. Learn more about Vercel for Git ↗︎

Name	Status	Preview	Comments	Updated
widgets	✅ Ready (Inspect)	Visit Preview	💬 Add your feedback	Mar 7, 2023 at 1:59AM (UTC)

[github-actions]

🎉 This PR is included in version 2.46.0 🎉

The release is available on:

• GitHub release
• npm package (@latest dist-tag)

Your semantic-release bot 📦🚀