Bump core-foundation-sys from 0.8.4 to 0.8.6

Bumps [core-foundation-sys](https://github.com/servo/core-foundation-rs) from 0.8.4 to 0.8.6.
- [Commits](servo/core-foundation-rs@core-foundation-sys-v0.8.4...core-foundation-sys-v0.8.6)

---
updated-dependencies:
- dependency-name: core-foundation-sys
  dependency-type: indirect
  update-type: version-update:semver-patch
...

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