High cpu usage when searching for $ or ^ in regular expressin mode

[n-wissam]

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Describe the bug Searching for $ or ^ in regular expression mode makes Typora freeze with high cpu usage

To Reproduce Steps to reproduce the behavior:

1. Go to 'Find'
2. Click on 'regular expression icon to activate regular expression mode'
3. Type '$ or ^'

Sample Markdown File The problem happens in any markdown file even empty ones

Desktop (please complete the following information):

• OS: [EndeavorOS (based on arch)]

Typora Version 1.3.6