fix: re-encode url to prevent fs.allow bypass (fixes #8498)

[sapphi-red]

Description

I think this fix is not the ideal way but at least it works.

The reason why #8498 (comment) was happening is:

1. Vite decodes URL (%252ffoo.txt => %2ffoo.txt)
2. Vite filters URL (%2ffoo.txt)
3. sirv decodes URL (%2ffoo.txt => /foo.txt)
4. sirv reponses (/foo.txt)

The file path mapped from URL is different between 2 and 4.

This PR adds encode after 2. (%2ffoo.txt => %252ffoo.txt)

fixes #8498
refs #8804
refs lukeed/sirv#139

Additional context

---

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the Commit Convention.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

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