fix(deps): update rust crate oci-spec to 0.6.8

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
oci-spec	dependencies	patch	0.6.7 -> 0.6.8

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Release Notes

containers/oci-spec-rs (oci-spec)

### [`v0.6.8`](https://togithub.com/containers/oci-spec-rs/releases/tag/v0.6.8) [Compare Source](https://togithub.com/containers/oci-spec-rs/compare/v0.6.7...v0.6.8) #### What's Changed ##### Runtime Specification - Validate `execCPUAffinity` of the runtime process spec by [@​keisku](https://togithub.com/keisku) in [https://github.com/containers/oci-spec-rs/pull/178](https://togithub.com/containers/oci-spec-rs/pull/178) - enhancement: Handle "mount" and "network" for LinuxNamespaceType by [@​Apokleos](https://togithub.com/Apokleos) in [https://github.com/containers/oci-spec-rs/pull/187](https://togithub.com/containers/oci-spec-rs/pull/187) ##### Test improvements and Misc Fixes - Enforce a label to a PR and generate release notes from labels by [@​utam0k](https://togithub.com/utam0k) in [https://github.com/containers/oci-spec-rs/pull/188](https://togithub.com/containers/oci-spec-rs/pull/188) - Specifying Dependencies with tilde requirements by [@​Apokleos](https://togithub.com/Apokleos) in [https://github.com/containers/oci-spec-rs/pull/191](https://togithub.com/containers/oci-spec-rs/pull/191) - Release 0.6.8 by [@​keisku](https://togithub.com/keisku) in [https://github.com/containers/oci-spec-rs/pull/189](https://togithub.com/containers/oci-spec-rs/pull/189) ##### Other Changes - Release 0.6.7 by [@​saschagrunert](https://togithub.com/saschagrunert) in [https://github.com/containers/oci-spec-rs/pull/182](https://togithub.com/containers/oci-spec-rs/pull/182) - \[breaking change] Fix default initialization of LinuxDeviceCgroup in LinuxResources by [@​Apokleos](https://togithub.com/Apokleos) in [https://github.com/containers/oci-spec-rs/pull/185](https://togithub.com/containers/oci-spec-rs/pull/185) **Full Changelog**: https://github.com/containers/oci-spec-rs/compare/v0.6.7...v0.6.8

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