[dependency]: Bump plotly from 5.24.1 to 6.6.0 in /explorer/nodewatch

Bumps [plotly](https://github.com/plotly/plotly.py) from 5.24.1 to 6.6.0.
- [Release notes](https://github.com/plotly/plotly.py/releases)
- [Changelog](https://github.com/plotly/plotly.py/blob/main/CHANGELOG.md)
- [Commits](plotly/plotly.py@v5.24.1...v6.6.0)

---
updated-dependencies:
- dependency-name: plotly
  dependency-version: 6.6.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

explorer/nodewatch/requirements.txt

@@ -2,7 +2,7 @@ aiohttp==3.13.3
 APScheduler==3.11.2
 Flask==3.1.3
 pandas==3.0.1
-plotly==5.24.1
+plotly==6.6.0
 symbol-sdk-python==3.3.0
 zenlog==1.1
 flask_cors==6.0.2