[feature] Gin enable gzip encoding (#405)

* add gin gzip dependency

* add gzip middleware to router

* go mod tidy

internal/router/gzip.go

@@ -0,0 +1,30 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package router
+
+import (
+	ginGzip "github.com/gin-contrib/gzip"
+	"github.com/gin-gonic/gin"
+)
+
+func useGzip(engine *gin.Engine) error {
+	gzipMiddleware := ginGzip.Gzip(ginGzip.DefaultCompression)
+	engine.Use(gzipMiddleware)
+	return nil
+}