deps(dev): bump ethers from 6.14.4 to 6.15.0

Bumps [ethers](https://github.com/ethers-io/ethers.js) from 6.14.4 to 6.15.0.
- [Release notes](https://github.com/ethers-io/ethers.js/releases)
- [Changelog](https://github.com/ethers-io/ethers.js/blob/main/CHANGELOG.md)
- [Commits](ethers-io/ethers.js@v6.14.4...v6.15.0)

---
updated-dependencies:
- dependency-name: ethers
  dependency-version: 6.15.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]