⬆️ Bump sphinx-exercise from 1.0.1 to 1.2.1 (#296)

* ⬆️ Bump sphinx-exercise from 1.0.1 to 1.2.1

Bumps [sphinx-exercise](https://github.com/executablebooks/sphinx-exercise) from 1.0.1 to 1.2.1.
- [Release notes](https://github.com/executablebooks/sphinx-exercise/releases)
- [Changelog](https://github.com/executablebooks/sphinx-exercise/blob/main/CHANGELOG.md)
- [Commits](executablebooks/sphinx-exercise@v1.0.1...v1.2.1)

---
updated-dependencies:
- dependency-name: sphinx-exercise
  dependency-version: 1.2.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

* Enable exercise_style solution_follow_exercise feature

---------

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

Author: dependabot[bot]

environment.yml

@@ -10,7 +10,7 @@ dependencies:
     - quantecon-book-theme==0.15.1
     - sphinx-tojupyter==0.6.0
     - sphinxext-rediraffe==0.2.7
-    - sphinx-exercise==1.0.1
+    - sphinx-exercise==1.2.1
     - sphinx-proof==0.3.0
     - sphinxcontrib-youtube==1.4.1
     - sphinx-togglebutton==0.3.2

lectures/_config.yml

@@ -118,6 +118,8 @@ sphinx:
           "gG": "\\mathcal{G}"
           "hH": "\\mathcal{H}"
     mathjax_path: https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js
+    # sphinx-exercise
+    exercise_style: "solution_follow_exercise"
     rediraffe_redirects:
       index_toc.md: intro.md
     tojupyter_static_file_path: ["source/_static", "_static"]