⬆️ Bump sphinx-tojupyter from 0.3.1 to 0.6.0 (#298)

Bumps [sphinx-tojupyter](https://github.com/QuantEcon/sphinx-tojupyter) from 0.3.1 to 0.6.0.
- [Release notes](https://github.com/QuantEcon/sphinx-tojupyter/releases)
- [Changelog](https://github.com/QuantEcon/sphinx-tojupyter/blob/main/CHANGELOG.md)
- [Commits](QuantEcon/sphinx-tojupyter@v0.3.1...v0.6.0)

---
updated-dependencies:
- dependency-name: sphinx-tojupyter
  dependency-version: 0.6.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

environment.yml

@@ -8,7 +8,7 @@ dependencies:
   - pip:
     - jupyter-book>=1.0.4post1,<2.0
     - quantecon-book-theme==0.15.1
-    - sphinx-tojupyter==0.3.1
+    - sphinx-tojupyter==0.6.0
     - sphinxext-rediraffe==0.2.7
     - sphinx-exercise==1.0.1
     - sphinx-proof==0.3.0