ARM update fails with 2023-08-01 when setting updateChannel property

Deploying Azure Cache for Redis instance with bicep template below.
The initial deployment works as expected without any issues.

Running deployment again when resource already exists results with error:
> "The unknown resource response code 'NotModified' is encountered."

Removing the line `updateChannel: 'Stable'` fixes the problem. `Stable` is the default either way.
The problem only affects version `2023-08-01` (older versions don't have this property).

```bicep
resource redis 'Microsoft.Cache/redis@2023-08-01' = {
name: 'redis-${uniqueString(resourceGroup().id)}'
location: resourceGroup().location
properties: {
sku: {
name: 'Basic'
family: 'C'
capacity: 0
}
redisConfiguration: {
'maxmemory-reserved': '30'
'maxfragmentationmemory-reserved': '30'
'maxmemory-delta': '30'
}
enableNonSslPort: false
redisVersion: '6.0'
publicNetworkAccess: 'Disabled'
minimumTlsVersion: '1.2'
updateChannel: 'Stable'
}
}
```

首先，使用 Microsoft.Cache/redis API 版本 2023-08-01 和 updateChannel 属性，复现 issue 的 Bicep 模板中的第二次部署。比较移除该属性后的行为，以及与较旧 API 版本的行为；当现有资源部署不再返回 NotModified 错误，同时保留预期的更新通道时，即表示完成。

由索引模型根据 Issue 内容生成。