chore: bump express from 4.18.2 to 4.20.0

[morrisonak]

Summary of Changes
This PR updates the express package from version 4.18.2 to 4.20.0 to resolve a peer dependency conflict with @remix-run/[email protected].

Error Report
While attempting to install dependencies, the following error was encountered:

npm resolution error report

While resolving: remix-shadcn@undefined
Found: [email protected]
node_modules/express
  express@"4.18.2" from the root project

Could not resolve dependency:
peer express@"^4.20.0" from @remix-run/[email protected]
node_modules/@remix-run/express
  @remix-run/express@"*" from the root project

This update ensures compatibility with the latest version of @remix-run/express.