fix(clerk-js): Make Select element themable

[desiprisg]

Type of change

• [x] 🐛 Bug fix
• [ ] 🌟 New feature
• [ ] 🔨 Breaking change
• [ ] 📖 Refactoring / dependency upgrade / documentation
• [ ] other:

Packages affected

• [x] @clerk/clerk-js
• [ ] @clerk/clerk-react
• [ ] @clerk/nextjs
• [ ] @clerk/remix
• [ ] @clerk/types
• [ ] @clerk/themes
• [ ] @clerk/clerk-expo
• [ ] @clerk/backend-core
• [ ] @clerk/clerk-sdk-node
• [ ] @clerk/edge
• [ ] build/tooling/chore

Description

• [x] npm test runs as expected.
• [x] npm run build runs as expected.