chore: v6 update node version for test builds

[jeff-phillips-18]

What

Fix node version for build testing

[jeff-phillips-18]

@nicolethoen @wise-king-sullyman Any idea why the test_a11y failure?

[wise-king-sullyman]

Looks like this problem actually started with the last commit that was merged into the v6 branch which bumped the versions of the PF packages, but beyond that I'm having a hard time debugging. Going back to the commit before that makes everything work fine, but manually undoing that bump still has the error 🤔

[jeff-phillips-18]

@wise-king-sullyman I reverted the version of the docs framework back to 5.2.15 and reverted to the yarn.lock from prior to the bump. Seems to have fixed the problem but now we need to figure out how to update the @patternfly/documentation-framework dependency going forward.