Bump rewriter from 26f5c84 to 20d3ab6

Bumps [rewriter](https://github.com/mit-plv/rewriter) from `26f5c84` to `20d3ab6`.
- [Release notes](https://github.com/mit-plv/rewriter/releases)
- [Commits](mit-plv/rewriter@26f5c84...20d3ab6)

---
updated-dependencies:
- dependency-name: rewriter
  dependency-type: direct:production
...

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