Move to the mattermost/go-i18n fork (#10669)

This change is being made to address an issue where the go-i18n
translation library would result in partial-translations when a
given language dictionary was missing a given plural keyword. The
improvement made here leads the translation library to try an
'other' keyword lookup if the first plural keyword fails to have
a value.

This change was not accepted upstream due to concern regarding
changing the behavior, so we are using a fork at this time to
address the issue.

app/server_test.go

@@ -230,7 +230,7 @@ func TestPanicLog(t *testing.T) {
 		ConsoleJson:   true,
 		EnableFile:    true,
 		FileLocation:  tmpfile.Name(),
-		FileLevel: mlog.LevelInfo,
+		FileLevel:     mlog.LevelInfo,
 	})
 
 	// Creating a server with logger