build(deps): bump pixi.js in /exoplanet-transit-simulator

Bumps [pixi.js](https://github.com/pixijs/pixijs) from 7.3.2 to 8.9.1.
- [Release notes](https://github.com/pixijs/pixijs/releases)
- [Commits](pixijs/pixijs@v7.3.2...v8.9.1)

---
updated-dependencies:
- dependency-name: pixi.js
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]