Use forked version of gziphandler (#17852)

web/handlers.go

@@ -14,7 +14,7 @@ import (
 	"strings"
 	"time"
 
-	"github.com/NYTimes/gziphandler"
+	"github.com/mattermost/gziphandler"
 	"github.com/opentracing/opentracing-go"
 	"github.com/opentracing/opentracing-go/ext"
 	spanlog "github.com/opentracing/opentracing-go/log"

web/static.go

@@ -9,7 +9,7 @@ import (
 	"path/filepath"
 	"strings"
 
-	"github.com/NYTimes/gziphandler"
+	"github.com/mattermost/gziphandler"
 
 	"github.com/mattermost/mattermost-server/v5/model"
 	"github.com/mattermost/mattermost-server/v5/shared/mlog"