Update docutils requirement from <0.21,>=0.14 to >=0.21.2,<0.22

Updates the requirements on [docutils](https://docutils.sourceforge.io) to permit the latest version.

---
updated-dependencies:
- dependency-name: docutils
  dependency-type: direct:production
...

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

Author: dependabot[bot]

Diff for: docs/requirements.txt

@@ -1,4 +1,4 @@
-docutils>=0.14,<0.21
+docutils>=0.21.2,<0.22
 ipykernel
 ipython
 jinja2>=3.0

Diff for: requirements.txt

@@ -1,6 +1,6 @@
 anaconda-client
 conda-build
-docutils>=0.14,<0.21
+docutils>=0.21.2,<0.22
 ipykernel
 ipython
 jinja2>=3.0

Diff for: setup.py

@@ -38,12 +38,12 @@ def get_version():
               'thermodynamics'],
     install_requires=['matplotlib', 'numpy', 'scipy'],
     extras_require={
-      'docs': ['docutils>=0.14,<0.21', 'ipykernel', 'ipython',
+      'docs': ['docutils>=0.21.2,<0.22', 'ipykernel', 'ipython',
                'jinja2>=3.0', 'nbsphinx', 'pycodestyle',
                'sphinx', 'sphinx-copybutton',
                'sphinx-rtd-theme', 'sphinxcontrib-bibtex'],
       'testing': ['pycodestyle', 'pylint', 'pytest', 'pytest-cov'],
-      'all': ['docutils>=0.14,<0.21', 'ipykernel', 'ipython', 'jinja2>=3.0',
+      'all': ['docutils>=0.21.2,<0.22', 'ipykernel', 'ipython', 'jinja2>=3.0',
               'nbsphinx', 'pycodestyle', 'pylint', 'pytest', 'pytest-cov',
               'sphinx', 'sphinx-copybutton',
               'sphinx-rtd-theme', 'sphinxcontrib-bibtex']