types: handler might be string or array of strings

[morriq]

Hello

handler as string[] is correctly displayed in metrics:

http_request_duration_milliseconds_count{handler="/tiles/:segments(*),/tiles",code="200",method="HEAD"} 3

but TS can't agree to use it:

[SimenB]

Happy to take a PR 🙂

[zbjornson]

I'm not sure if that is works by intent or chance, actually. If you want to make it PR, it would need to add tests in addition to the typescript declaration changes.