Child encoder module is hardcoded to only 3 built-in ones

[francislavoie]

I told some users in caddyserver/transform-encoder#18 (comment) that they could use this plugin along with the transform encoder, but apparently this plugin doesn't allow it because of the switch here:

caddy-conditional-logging/plugin.go

Line 171 in 8534d30

switch v := val.(type) {

This plugin should allow any encoder module to be a child.

(That said, there's now a skip_log directive built into Caddy since v2.6 so this plugin probably isn't really needed anymore)