build(deps-dev): bump @rollup/plugin-typescript in /clients/js-legacy

Bumps [@rollup/plugin-typescript](https://github.com/rollup/plugins/tree/HEAD/packages/typescript) from 12.1.1 to 12.1.2.
- [Changelog](https://github.com/rollup/plugins/blob/master/packages/typescript/CHANGELOG.md)
- [Commits](https://github.com/rollup/plugins/commits/typescript-v12.1.2/packages/typescript)

---
updated-dependencies:
- dependency-name: "@rollup/plugin-typescript"
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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Author: dependabot[bot]