feat(chart): make timezone configurable for the act_runner (#38)

Once: https://gitea.com/gitea/act_runner/pulls/738
Is merged.
Then this can be applied to specify timezone for example for cases such as:

![image.png](/attachments/436c1772-da20-4904-af0b-cb5111d6c6cf)

Right now the correct time has to be retrieved with a ENV variable in the cmd: `git commit -m "Update custom ISO: $(TZ=Europe/Amsterdam date +'%Y-%m-%d %H:%M')" || echo "No changes to commit"`

Co-authored-by: Daan Selen <dselen@systemec.nl>
Reviewed-on: https://gitea.com/gitea/helm-actions/pulls/38
Reviewed-by: techknowlogick <techknowlogick@noreply.gitea.com>
Co-authored-by: Daan Selen <dselen@nerthus.nl>
Co-committed-by: Daan Selen <dselen@nerthus.nl>

templates/statefulset.yaml

@@ -64,6 +64,8 @@ spec:
               value: {{ include "gitea.actions.local_root_url" . }}
             - name: CONFIG_FILE
               value: /actrunner/config.yaml
+            - name: TZ
+              value: {{ .Values.statefulset.timezone | default "Etc/UTC" }}
           resources:
             {{- toYaml .Values.statefulset.resources | nindent 12 }}
           volumeMounts: