Echo: BodyDump can discard BodyLimit overflow errors for unknown-length requests

Echo is a Go web framework. From 5.0.0 until 5.4.1, Echo v5's BodyDump middleware can discard a BodyLimit overflow error for an unknown-length request when BodyDump's capture limit is below the BodyLimit threshold. BodyDump drains the remaining body while ignoring read errors and replaces it with the captured prefix, so an HTTP/1.1 chunked request can be truncated and processed successfully even though the original body exceeded the configured limit. Known-length requests rejected before BodyDump runs are unaffected, and the issue does not establish a general authentication bypass or denial of service. This issue is fixed in 5.4.1.