Fix yaml parse error: @ cannot start a string (#80)

* FIx yaml parse error: @ cannot start a string

Helm 3.5.0 (not tested with earlier versions)

The `schedule` var value is `@hourly`. The `@` produces this error:

> error converting YAML to JSON: yaml: line 47: found character that cannot start any token

Quoting the string fixes the issue.

* Update cronjob.yaml

Updated by PR comment

Co-authored-by: Øystein Bedin <oybed@users.noreply.github.com>

charts/cronjob-ldap-group-sync-secure/templates/cronjob.yaml

@@ -44,5 +44,5 @@ spec:
           - name: ldap-bind-password
             secret:
               secretName: {{ .Values.ldap_bind_password_secret }}
-  schedule: {{ .Values.schedule }}
+  schedule: {{ .Values.schedule | quote }}
   successfulJobsHistoryLimit: {{ .Values.success_jobs_history_limit }}