[BRANDING] Update nodeinfo branding

- Change the values for the nodeinfo API, to use branded values.
- Resolves https://codeberg.org/forgejo/forgejo/issues/257

(cherry picked from commit fa5130a663)

tests/integration/api_nodeinfo_test.go

@@ -31,7 +31,7 @@ func TestNodeinfo(t *testing.T) {
 		var nodeinfo api.NodeInfo
 		DecodeJSON(t, resp, &nodeinfo)
 		assert.True(t, nodeinfo.OpenRegistrations)
-		assert.Equal(t, "gitea", nodeinfo.Software.Name)
+		assert.Equal(t, "forgejo", nodeinfo.Software.Name)
 		assert.Equal(t, 24, nodeinfo.Usage.Users.Total)
 		assert.Equal(t, 17, nodeinfo.Usage.LocalPosts)
 		assert.Equal(t, 2, nodeinfo.Usage.LocalComments)