ci: fix playwright cache

[sapphi-red]

Description

playwright cache wasn't working and this PR fixes that.
https://github.com/vitejs/vite/actions/runs/3645678953/jobs/6156032178#step:9:11

I thought actions/cache saves the directory if it's changed. But I noticed that it only saves when the cache didn't hit.
https://github.com/vitejs/vite/actions/runs/3645678953/jobs/6156032178#step:25:2

refs #8599

Additional context

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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