Typo in CallAutomation_OutboundCalling/src/app.ts

> Please provide us with the following information:
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### This issue is for a: (mark with an `x`)
```
- [X] bug report -> please search issues before submitting
- [ ] feature request
- [ ] documentation issue or request
- [ ] regression (a behavior that used to work and stopped in a new release)
```

### Minimal steps to reproduce
>Purposely make a TextSource / FileSource / SsmlSource fail to reporduce.

### Any log messages given by the failure
>
Call back event received, callConnectionId=xxxx-xxxx-xxxx, serverCallId=yyyyyyyyyy, eventType=Microsoft.Communication.**PlayFailed**

### Expected/desired behavior
>The call should be terminated.

### OS and Version?
> Node.js running on Windows

### Versions
> Commit d46e964 (latest when opening this issue)

### Mention any other details that might be useful
Hello, I'd like to report a type error in line 161 of the file CallAutomation_OutboundCalling/src/app.ts, the event checked should be "Microsoft.Communication.**P**layFailed" but it's "Microsoft.Communication.**p**layFailed".
This causes the call to not be terminated in case of a failure while playing the message.
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> Thanks! We'll be in touch soon.

CallAutomation_OutboundCalling/src/app.ts の 161 行目を開き、Microsoft.Communication.PlayFailed の callback 処理を確認します。TextSource、FileSource、または SsmlSource の再生失敗を再現し、修正されたイベントが認識されて通話が終了することを確認します。

索引モデルが issue の本文から書いたものです。