fix: Add transifex flag.

The Transifex cli started requiring the -t or --translations flag in the pull command in order to fetch translations.

edx/edx-arch-experiments#77

Author: dianakhuang

Makefile

@@ -50,7 +50,7 @@ push_translations:
 
 # Pulls translations from Transifex.
 pull_translations:
-	tx pull -f --mode reviewed --languages=$(transifex_langs)
+	tx pull -t -f --mode reviewed --languages=$(transifex_langs)
 
 # This target is used by Travis.
 validate-no-uncommitted-package-lock-changes: