Bump sphinx-autobuild from 0.6.0 to 2021.3.14

Bumps [sphinx-autobuild](https://github.com/executablebooks/sphinx-autobuild) from 0.6.0 to 2021.3.14.
- [Release notes](https://github.com/executablebooks/sphinx-autobuild/releases)
- [Changelog](https://github.com/executablebooks/sphinx-autobuild/blob/main/NEWS.rst)
- [Commits](https://github.com/executablebooks/sphinx-autobuild/commits)

---
updated-dependencies:
- dependency-name: sphinx-autobuild
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements/docs.txt

@@ -1,3 +1,3 @@
 sphinx==4.3.1
-sphinx-autobuild==0.6.0
+sphinx-autobuild==2021.3.14
 jinja2==2.11.3

requirements/rtd.txt

@@ -1,5 +1,5 @@
 sphinx==4.3.1
-sphinx-autobuild==0.6.0
+sphinx-autobuild==2021.3.14
 jinja2==2.11.3
 future==0.18.2
 raven==6.10.0