Pass the date field in to the Spec11 Soy template

The daily template is the only one that needs it but we can always pass it in without issue.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=231295089

java/google/registry/reporting/spec11/Spec11EmailUtils.java

@@ -141,6 +141,7 @@ public class Spec11EmailUtils {
 
     Map<String, Object> data =
         ImmutableMap.of(
+            "date", date.toString(),
             "registry", registryName,
             "replyToEmail", spec11ReplyToAddress,
             "threats", threatMatchMap,