chore: Fix readthedocs builds (#190)

Author: farleyb-amazon

.readthedocs.yaml

@@ -0,0 +1,22 @@
+# .readthedocs.yaml
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+# Required
+version: 2
+
+# Build documentation in the doc/ directory with Sphinx
+sphinx:
+   configuration: doc/conf.py
+
+# Don't need to build documentation for test vectors or any other
+# sub modules
+submodules:
+  exclude: all
+
+python:
+  version: 3.8
+  install:
+    - requirements: doc/requirements.txt
+    - method: setuptools
+      path: .

doc/requirements.txt

@@ -1,2 +1,2 @@
-sphinx>=1.3.0
-sphinx_rtd_theme
+sphinx==4.2.0
+sphinx_rtd_theme==1.0.0