Bump leptos from 0.6.15 to 0.7.0 in /pixie-web

Bumps [leptos](https://github.com/leptos-rs/leptos) from 0.6.15 to 0.7.0.
- [Release notes](https://github.com/leptos-rs/leptos/releases)
- [Commits](leptos-rs/leptos@v0.6.15...v0.7.0)

---
updated-dependencies:
- dependency-name: leptos
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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