GitHub alerts are formatted wrongly when there is more than one trailing space in headers

[brc-dd]

Describe the bug

dprint-plugin-markdown version: 0.19.0

Input Code

> [!IMPORTANT]  
> Crucial information necessary for users to succeed.

Expected Output

> [!IMPORTANT]
> Crucial information necessary for users to succeed.

Actual Output

> [!IMPORTANT]\
> Crucial information necessary for users to succeed.

https://dprint.dev/playground/#code/HwAg2ghAkgsgCgeQEoBUCCA5FBdAUKAYQCcBXAYwEsBDAGxAoDsAzAeyIFsqAXClhkBgFMyggM6iqRAJ4hWRECVGCiokFxYhR5EYIAmAOlz5w0eMnRZsIY8XLU6jOZx58BwsROmy2CpSrUaWmQ6BkagkLCIqJg4INaEpJS09Mxszrz8QiLikjJyvsqq6pragnqGQA/plugin/markdown