middleware proxy pass origin Host header

[art-frela]

Issue Description

Requests that reach the final server contain the Host header from the original request. If the destination server checks the header Host (eg: ingress in k8s cluster with Host rules) and if the values ​​do not match, then the request is rejected or etc...

Checklist

• Dependencies installed
• No typos
• Searched existing issues and docs

Expected behaviour

proxy replace request.Host to target.URL.Host

Actual behaviour

request.Host stay immutable

Steps to reproduce

• http server which checks Host header (srv1)
• http server with echo using middleware proxy (proxy) - target url to srv1, domain for proxy <> domain for srv1
• run both srv1 and proxy
• request to proxy

client (localhost) --(Host: proxy.domain.com)--> proxy (proxy.domain.com) --(Host: proxy.domain.com)--> srv1 (srv1.domain.com)

Version/commit

echo v4.12.0

dirty workaround

• use vendoring
• add to github.com/labstack/echo/v4/middleware/proxy.go

req.Host = tgt.URL.Host

P.S. Maybe add option to ProxyConfig