refs #9 update sphinx and add rtd theme

Author: takanory

constraints.txt

@@ -1,28 +1,29 @@
 alabaster==0.7.12
 attrs==21.2.0
 Babel==2.9.1
-certifi==2021.5.30
-charset-normalizer==2.0.4
+certifi==2021.10.8
+charset-normalizer==2.0.7
 docutils==0.17.1
-idna==3.2
+idna==3.3
 imagesize==1.2.0
-Jinja2==3.0.1
+Jinja2==3.0.2
 markdown-it-py==1.1.0
 MarkupSafe==2.0.1
 mdit-py-plugins==0.2.8
-myst-parser==0.15.1
+myst-parser==0.15.2
 packaging==21.0
 Pygments==2.10.0
-pyparsing==2.4.7
-pytz==2021.1
-PyYAML==5.4.1
+pyparsing==3.0.3
+pytz==2021.3
+PyYAML==6.0
 requests==2.26.0
 snowballstemmer==2.1.0
-Sphinx==4.1.2
+Sphinx==4.2.0
+sphinx-rtd-theme==1.0.0
 sphinxcontrib-applehelp==1.0.2
 sphinxcontrib-devhelp==1.0.2
 sphinxcontrib-htmlhelp==2.0.0
 sphinxcontrib-jsmath==1.0.1
 sphinxcontrib-qthelp==1.0.3
 sphinxcontrib-serializinghtml==1.1.5
-urllib3==1.26.6
+urllib3==1.26.7

requirements.txt

@@ -1,2 +1,3 @@
 Sphinx
 myst-parser
+sphinx-rtd-theme