Allow paths to be excluded when using ForceHTTPS

[andrewthetechie]

Description of the feature

I use the ForceHTTPS middleware to redirect requests to HTTPS for my app. Unfortunately, this causes problems when deploying in k8s with health checks.

I'd like to be able to exclude a path from ForceHTTPS

[sunli829]

I added a filter method, which should solve the problem.

https://github.com/poem-web/poem/blob/80f118adce6819914dce254a1815adf16572d94a/poem/src/middleware/force_https.rs#L33

[andrewthetechie]

Very cool! Thanks :)