Add dep for docs-path-filter job (rerun-io#5818)

### What
Needed for the filter to work properly.

### Checklist
* [x] I have read and agree to [Contributor
Guide](https://github.com/rerun-io/rerun/blob/main/CONTRIBUTING.md) and
the [Code of
Conduct](https://github.com/rerun-io/rerun/blob/main/CODE_OF_CONDUCT.md)
* [x] I've included a screenshot or gif (if applicable)
* [x] I have tested the web demo (if applicable):
* Using newly built examples:
[rerun.io/viewer](https://rerun.io/viewer/pr/5818)
* Using examples from latest `main` build:
[rerun.io/viewer](https://rerun.io/viewer/pr/5818?manifest_url=https://app.rerun.io/version/main/examples_manifest.json)
* Using full set of examples from `nightly` build:
[rerun.io/viewer](https://rerun.io/viewer/pr/5818?manifest_url=https://app.rerun.io/version/nightly/examples_manifest.json)
* [x] The PR title and labels are set such as to maximize their
usefulness for the next release's CHANGELOG
* [x] If applicable, add a new check to the [release
checklist](https://github.com/rerun-io/rerun/blob/main/tests/python/release_checklist)!

- [PR Build Summary](https://build.rerun.io/pr/5818)
- [Recent benchmark results](https://build.rerun.io/graphs/crates.html)
- [Wasm size tracking](https://build.rerun.io/graphs/sizes.html)

.github/workflows/on_pull_request.yml

@@ -207,6 +207,7 @@ jobs:
   deploy-landing-preview:
     name: "Deploy Landing Preview"
     if: needs.docs-paths-filter.outputs.docs_changes == 'true'
+    needs: docs-paths-filter
     uses: ./.github/workflows/reusable_deploy_landing_preview.yml
     with:
       CONCURRENCY: pr-${{ github.event.pull_request.number }}