ci(py-deps): bump myst-nb from 1.3.0 to 1.4.0 (#367)

Bumps [myst-nb](https://github.com/executablebooks/myst-nb) from 1.3.0 to 1.4.0.
- [Release notes](https://github.com/executablebooks/myst-nb/releases)
- [Changelog](https://github.com/executablebooks/MyST-NB/blob/main/CHANGELOG.md)
- [Commits](executablebooks/MyST-NB@v1.3.0...v1.4.0)

---
updated-dependencies:
- dependency-name: myst-nb
  dependency-version: 1.4.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

poetry.lock

@@ -29,7 +29,7 @@ pytest-cov = { version = ">=6.0,<7.1", optional = true }
 qiskit-ibm-provider = { version = ">=0.11,<0.12", optional = true }
 ruff = { version = ">=0.8,<0.16", optional = true }
 furo = { version = ">=2024.8,<2025.13", optional = true }
-myst-nb = { version = ">=1.1,<1.4", optional = true }
+myst-nb = { version = ">=1.1,<1.5", optional = true }
 sphinx-autodoc-typehints = { version = ">=2.5,<3.3", optional = true }
 jupyter-sphinx = { version = ">=0.5,<0.6", optional = true}