fix: add `cypress install` to `prepare` script to fix pnpm 10 compatibility

fix: add `cypress install` to `prepare` script to fix pnpm 10 compatibility

This approach works with both pnpm 10 and other package managers:
- If Cypress's `postinstall` script has been run, it'll do nothing other
than print a message.
- If `postinstall` hasn't been run, it'll download the Cypress binary.

As for why using `prepare` instead of `postinstall`, please refer to the
discussion thread where `husky` decided to use `prepare`:
- <https://github.com/typicode/husky/issues/884>