fix typo

https://github.com/vim-jp/lang-ja/pull/55/files/09dbfa996177b38633466461c78c6fd43ccdf39c#r76994684
https://github.com/vim-jp/lang-ja/pull/55/files/09dbfa996177b38633466461c78c6fd43ccdf39c#r76995367

Author: koron

src/po/ja.po

@@ -221,7 +221,7 @@ msgid "E904: last argument for expr/call must be a number"
 msgstr "E904: expr/call の最後の引数は数字でなければなりません"
 
 msgid "E904: third argument for call must be a list"
-msgstr "E686: call の3番めの引数はリスト型でなければなりません"
+msgstr "E904: call の3番目の引数はリスト型でなければなりません"
 
 #, c-format
 msgid "E905: received unknown command: %s"