build(deps): bump lib/zig-datetime from 1334f86 to 768776a

Bumps [lib/zig-datetime](https://github.com/frmdstryr/zig-datetime) from `1334f86` to `768776a`.
- [Release notes](https://github.com/frmdstryr/zig-datetime/releases)
- [Commits](frmdstryr/zig-datetime@1334f86...768776a)

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

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