Add frozen string literal comment to files.

Add frozen string literal comment to files.

diff --git a/app/jobs/concerns/alert_post_mixin.rb b/app/jobs/concerns/alert_post_mixin.rb
index 686b7fc..b07f222 100644
--- a/app/jobs/concerns/alert_post_mixin.rb
+++ b/app/jobs/concerns/alert_post_mixin.rb
@@ -89,7 +89,7 @@ module AlertPostMixin
   def local_date(time)
     parsed = Time.zone.parse(time)
 
-    date = <<~DATE
+    date = +<<~DATE
     [date=#{parsed.strftime("%Y-%m-%d")} time=#{parsed.strftime("%H:%M:%S")} format="L HH:mm:ss" displayedTimezone="UTC" timezones="Europe/Paris\\|America/Los_Angeles\\|Asia/Singapore\\|Australia/Sydney"]
     DATE

GitHub sha: f68c2417