refactor: remove unused secretName template variable (#12)

### Description of the change

Removes unused variable in template, does not change existing behavior

Reviewed-on: https://gitea.com/gitea/helm-actions/pulls/12
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Christopher Homberger <christopher.homberger@web.de>
Co-committed-by: Christopher Homberger <christopher.homberger@web.de>

templates/rolebinding-job.yaml

@@ -1,7 +1,6 @@
 {{- if .Values.enabled }}
 {{- if and (and .Values.provisioning.enabled .Values.persistence.enabled) .Values.persistence.mount }}
 {{- $name := include "gitea.workername" (dict "global" . "worker" "actions-token-job") }}
-{{- $secretName := include "gitea.workername" (dict "global" . "worker" "actions-token") }}
 ---
 apiVersion: rbac.authorization.k8s.io/v1
 kind: RoleBinding