build(deps): bump lib/zig-datetime from 768776a to 70aebf2

Bumps [lib/zig-datetime](https://github.com/frmdstryr/zig-datetime) from `768776a` to `70aebf2`.
- [Release notes](https://github.com/frmdstryr/zig-datetime/releases)
- [Commits](frmdstryr/zig-datetime@768776a...70aebf2)

---
updated-dependencies:
- dependency-name: lib/zig-datetime
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>