changes to `kernel/` directory require `validation` check

[jacobweinstock]

The validation check is required for all PR's and will not run for changes only in the kernel/ directory. This causes PRs like #144 to not meet the merge criteria and therefore not meet all merge requirements.

Expected Behaviour

A change only in thekernel/ directory is still able to satisfy all PR checks.

Current Behaviour

Possible Solution

Steps to Reproduce (for bugs)

Context

Your Environment

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