ci: use gci linter (#5708)

* use gofmput to format code

* use gci to format imports

* reconfigure gci

* linter autofixes

* rearrange imports a little

* export GOOS=windows golangci-lint run ./... --fix

modules/caddyhttp/reverseproxy/upstreams.go

@@ -11,8 +11,9 @@ import (
 	"sync"
 	"time"
 
-	"github.com/caddyserver/caddy/v2"
 	"go.uber.org/zap"
+
+	"github.com/caddyserver/caddy/v2"
 )
 
 func init() {