The deprecated DOMNodeInserted should be removed and replaced with MutationObserver

[TacKana]

Version
@vueup/vue-quill version [e.g. 1.0.0-beta.5]

Describe the bug
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最新版的VueQuill内部还在使用一个已经废弃了的事件，这个事件会导致不兼容最新版本的浏览器，需要更换为更安全的事件MutationObserver

To Reproduce
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1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior
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• Browser [e.g. chrome, safari]
• Version [e.g. 22]

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