Update python-dotenv requirement from >=1.0 to >=1.2.3

Updates the requirements on [python-dotenv](https://github.com/theskumar/python-dotenv) to permit the latest version.
- [Release notes](https://github.com/theskumar/python-dotenv/releases)
- [Changelog](https://github.com/theskumar/python-dotenv/blob/main/CHANGELOG.md)
- [Commits](theskumar/python-dotenv@v1.0.0...v1.2.3)

---
updated-dependencies:
- dependency-name: python-dotenv
  dependency-version: 1.2.2
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements.txt

@@ -74,7 +74,7 @@ python-frontmatter
 # hands the gate policy to. The [flask] extra is just flask>=2.0, already
 # present via Dash.
 dash-improve-my-llms[flask]>=2.6.0
-python-dotenv>=1.0
+python-dotenv>=1.2.3
 pydantic>=2.0
 requests>=2.31