Fixup "can't evaluate field Count in type string"

After moving to the latest version of Hugo, we are seeing lots of warnings
as follows:

WARN 2021/03/08 10:11:09 Failed to get translated string for language "en" and ID "postedOnDate": template: :1:13: executing "" at <.Count>: can't evaluate field Count in type string

The fix is trivial, so implement to save these messages from obscuring
actual issues.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>

themes/beautifulhugo/i18n/en.yaml

@@ -2,7 +2,7 @@
 - id: dateFormat
   translation: "January 2, 2006"
 - id: postedOnDate
-  translation: "Posted on {{ .Count }}"
+  translation: "Posted on {{ . }}"
 - id: translationsLabel
   translation: "Other languages: "
 - id: translationsSeparator

themes/beautifulhugo/i18n/ja.yaml

@@ -2,7 +2,7 @@
 - id: dateFormat
   translation: "2006年1月2日"
 - id: postedOnDate
-  translation: "{{ .Count }}に投稿"
+  translation: "{{ . }}に投稿"
 - id: translationsLabel
   translation: "翻訳："
 - id: translationsSeparator

themes/beautifulhugo/i18n/ru.yaml

@@ -2,7 +2,7 @@
 - id: dateFormat
   translation: "Январь 2, 2006"
 - id: postedOnDate
-  translation: "Опубликовано {{ .Count }}"
+  translation: "Опубликовано {{ . }}"
 - id: translationsLabel
   translation: "Другие языки: "
 - id: translationsSeparator