Update docs requirements

Author: domdfcoding

doc-source/requirements.txt

@@ -1,9 +1,8 @@
-git+https://github.com/sphinx-toolbox/html-section.git
-git+https://github.com/sphinx-toolbox/sphinx-licenseinfo.git
-default-values>=0.5.0
-extras-require>=0.2.0
-furo>=2020.11.19b18
-seed-intersphinx-mapping>=0.3.1
+default-values>=0.6.0
+extras-require>=0.5.0
+furo==2021.06.18b36
+html-section>=0.3.0
+seed-intersphinx-mapping>=1.2.2
 sphinx<3.4.0,>=3.0.3
 sphinx-copybutton>=0.2.12
 sphinx-debuginfo>=0.2.2