Add Japanese translations for week(s) (#659)

ryuuji · systemcatch · commit 9b0521697b3d · 2019-09-10T11:00:03.000+01:00
diff --git a/arrow/locales.py b/arrow/locales.py
@@ -588,6 +588,8 @@ class JapaneseLocale(Locale):
         "hours": "{0}時間",
         "day": "1日",
         "days": "{0}日",
+        "week": "1週間",
+        "weeks": "{0}週間",
         "month": "1ヶ月",
         "months": "{0}ヶ月",
         "year": "1年",
