Bump devcert from 1.1.0 to 1.2.1 in /docs

Bumps [devcert](https://github.com/davewasmer/devcert) from 1.1.0 to 1.2.1.
- [Release notes](https://github.com/davewasmer/devcert/releases)
- [Changelog](https://github.com/davewasmer/devcert/blob/master/CHANGELOG.md)
- [Commits](davewasmer/devcert@v1.1.0...v1.2.1)

---
updated-dependencies:
- dependency-name: devcert
  dependency-type: indirect
...

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Author: dependabot[bot]