docs: tweak voice.svg

[sapphi-red]

Description

Changed voice.svg a bit.
Also fixed vitepress failing to build after #8623. (For example, https://github.com/vitejs/vite/runs/6943641928?check_suite_focus=true)

Before

After

Additional context

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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