Bump plotly from 5.18.0 to 5.21.0

Bumps [plotly](https://github.com/plotly/plotly.py) from 5.18.0 to 5.21.0.
- [Release notes](https://github.com/plotly/plotly.py/releases)
- [Changelog](https://github.com/plotly/plotly.py/blob/master/CHANGELOG.md)
- [Commits](plotly/plotly.py@v5.18.0...v5.21.0)

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

Signed-off-by: dependabot[bot] <support@github.com>

requirements.txt

@@ -2,4 +2,4 @@ Flask==3.0.2
 ruamel.yaml==0.18.6
 monty==2024.4.17
 pymongo==4.7.0
-plotly==5.18.0
+plotly==5.21.0