Bump pypandoc from 1.11 to 1.13 in /requirements (#1539)

Bumps [pypandoc](https://github.com/JessicaTegner/pypandoc) from 1.11 to 1.13.
- [Release notes](https://github.com/JessicaTegner/pypandoc/releases)
- [Changelog](https://github.com/JessicaTegner/pypandoc/blob/master/release.md)
- [Commits](JessicaTegner/pypandoc@v1.11...v1.13)

---
updated-dependencies:
- dependency-name: pypandoc
  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>
Co-authored-by: Paul Profizi <[email protected]>

Author: dependabot[bot]

requirements/requirements_docs.txt

@@ -4,7 +4,7 @@ graphviz==0.20.1
 imageio==2.34.1
 imageio-ffmpeg==0.4.7
 nbsphinx==0.9.3
-pypandoc==1.11
+pypandoc==1.13
 pytest-sphinx==0.6.2
 pyvista==0.36.1
 sphinx==7.1.0