checks: update undervoltage grep pattern to match in newer kernels

[alexgg]

Change-type: patch

Hey there, appreciated contributor!

Have you taken a look at the contribution guidelines for this project? To enable our CI to work correctly and version the releases of the project, you need to ensure your commit messages contain the required information detailed here. Thank you!

[jellyfish-bot]

[dfunckt] This has attached https://jel.ly.fish/14162b48-b30e-4426-a4c1-b9619d91d668

[alexgg]

lgtm