Update nielsvaneck/render-md-mermaid action to v3

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
nielsvaneck/render-md-mermaid	action	major	v2 -> v3

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Release Notes

nielsvaneck/render-md-mermaid (nielsvaneck/render-md-mermaid)

### [`v3`](https://togithub.com/nielsvaneck/render-md-mermaid/releases/tag/v3) [Compare Source](https://togithub.com/nielsvaneck/render-md-mermaid/compare/v2...v3) Now with: - a license file in the repo - workflow execution limited to `*.md` changes only - removal of timestamps causes otherwise non-changed `.svg` files to stay unaltered - includes [#​14](https://togithub.com/nielsvaneck/render-md-mermaid/issues/14), which should fix [#​13](https://togithub.com/nielsvaneck/render-md-mermaid/issues/13)

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Configuration

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🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

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• [ ] If you want to rebase/retry this PR, check this box

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