Skip gzip for some well-known compressed file types (#30796)

Co-authored-by: silverwind <me@silverwind.io>
(cherry picked from commit be112c1fc30f87a248b30f48e891d1c8c18e8280)

Conflicts:
	routers/web/web.go
	trivial conflict because of https://codeberg.org/forgejo/forgejo/pulls/1533

tests/integration/repo_archive_test.go

@@ -0,0 +1,31 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package integration
+
+import (
+	"io"
+	"net/http"
+	"testing"
+
+	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/test"
+	"code.gitea.io/gitea/routers"
+	"code.gitea.io/gitea/tests"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRepoDownloadArchive(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+	defer test.MockVariableValue(&setting.EnableGzip, true)()
+	defer test.MockVariableValue(&testWebRoutes, routers.NormalRoutes())()
+
+	req := NewRequest(t, "GET", "/user2/repo1/archive/master.zip")
+	req.Header.Set("Accept-Encoding", "gzip")
+	resp := MakeRequest(t, req, http.StatusOK)
+	bs, err := io.ReadAll(resp.Body)
+	assert.NoError(t, err)
+	assert.Empty(t, resp.Header().Get("Content-Encoding"))
+	assert.Equal(t, 320, len(bs))
+}