Upgrade to router.fetch

[Cyb3r-Jak3]

Swap router.handle to router.fetch. router.handle is being dropped in itty-router@v5

https://itty.dev/itty-router/migrations/v4-v5#_1-router-handle-is-deprecated-in-favor-of-router-fetch

[harryzcy]

At some point in v4, we began to support (at the cost of extra bytes) boththe original router.handle and the newer router.fetch

Do you know from what version they started supporting that? Probably good to bump minor version of itty-router to make sure it's supported

[Cyb3r-Jak3]

Looks like v4.0.27 based of this commit, kwhitley/itty-router@53da003.