chore(dependencies): Update execa requirement to ^0.9.0 (#575)
chore(dependencies): Update execa requirement to ^0.9.0 (#575)

Updates the requirements on [execa](https://github.com/sindresorhus/execa) to permit the latest version.
- [Commits](https://github.com/sindresorhus/execa/commits/v0.9.0)
stryker-mutator/stryker,stryker-mutator/stryker,stryker-mutator/stryker