Bump once_cell from 1.7.2 to 1.8.0
Bumps [once_cell](https://github.com/matklad/once_cell) from 1.7.2 to 1.8.0.
- [Release notes](https://github.com/matklad/once_cell/releases)
- [Changelog](https://github.com/matklad/once_cell/blob/master/CHANGELOG.md)
- [Commits](https://github.com/matklad/once_cell/compare/v1.7.2...v1.8.0)
---
updated-dependencies:
- dependency-name: once_cell
dependency-type: direct:production
update-type: version-update:semver-minor
...
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dependabot[bot]