Bump `date-fns` to v5

New version focus on bundle size reduction and is currently in alpha
https://github.com/date-fns/date-fns/releases/tag/v5.0.0-alpha.0

There shouldn't be relevant breaking changes. We might either bump directly to alpha version or wait till stable release.

Read the linked date-fns v5 alpha release notes first, then inspect the project's dependency declarations to determine where the version is recorded. Resolve whether to use the alpha or wait for stable, update the dependency, and run the repository's existing checks; done means the chosen version is consistently recorded without regressions.

Vom Indexierungsmodell aus dem Issue-Text verfasst.