Pin peculiar beats to "7" for version install

Author: widhalmt

Diff for: molecule/beats_peculiar/converge.yml

@@ -21,6 +21,7 @@
     elasticsearch_jna_workaround: true
     elasticsearch_disable_systemcallfilterchecks: true
     elastic_stack_full_stack: false
+    elastic_release: 7
     filebeat_mysql_slowlog_input: true
     beats_auditbeat: true
     beats_auditbeat_version: latest