Use polka instead of Express

[cktang88]

Since we only use Express for like one tiny file, might as well use Polka https://github.com/lukeed/polka
compatible with express middleware, 90 LOC, no external deps

[konoikon]

I'm not sure if we want to proceed with this option. Since Polka hasn't released its first version yet, there is no type declaration file available through npm.

However, if we want to proceed, this guy created a custom declaration file that is supported and edited by polka's author. How would you like to proceed with this?

[cktang88]

Ah I see. Thanks for investigating this. I think we should probably wait until the official types come out to implement this, shouldn't be too long.

For people following this, the link tracking types support here: lukeed/polka#17

[bencooper222]

Project looks dead.