Bug: gateway.annotations did not find expected key

1、尝试修改annotations内容的时候发生报错
```
templates/service-gateway.yaml

annotations:
{{- range $key, $value := .Values.gateway.annotations }}
{{ $key }}: {{ $value | quote }}
{{- end }}

```
Error: UPGRADE FAILED: YAML parse error on apisix/templates/service-gateway.yaml: error converting YAML to JSON: yaml: line 24: did not find expected key
2、将 templates/service-gateway.yaml 改为如下内容问题修复；
```
annotations:
{{- with .Values.gateway.annotations }}
{{- toYaml . | nindent 4 }}
{{- end }}
```

Start with templates/service-gateway.yaml and the gateway.annotations values used by the chart. Render the chart with those annotations using Helm and inspect the generated YAML around the Service metadata. Done means the chart renders without a YAML parse error and the configured annotations appear correctly.

Written by the indexing model from the issue text.