Add ReadTheDocs config file

[skip ci]

.readthedocs.yaml

@@ -0,0 +1,23 @@
+# .readthedocs.yaml
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+# Required
+version: 2
+
+build:
+  os: ubuntu-22.04
+  tools:
+    python: "3.11"
+
+formats:
+  - epub
+
+sphinx:
+  configuration: docs/conf.py
+
+python:
+  install:
+  - requirements: requirements.txt
+  - requirements: requirements-dev.txt
+  - requirements: requirements-docs.txt

docs/conf.py

@@ -66,7 +66,7 @@
 #
 # This is also used if you do content translation via gettext catalogs.
 # Usually you set "language" from the command line for these cases.
-language = None
+language = "en"
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
@@ -82,15 +82,7 @@
 
 # -- Options for HTML output ----------------------------------------------
 
-# The theme to use for HTML and HTML Help pages.  See the documentation for
-# a list of builtin themes.
-#
-on_rtd = os.environ.get("READTHEDOCS", None) == "True"
-
-if not on_rtd:
-    import sphinx_rtd_theme
-    html_theme = 'sphinx_rtd_theme'
-    html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
+html_theme = 'sphinx_rtd_theme'
 
 # Theme options are theme-specific and customize the look and feel of a theme
 # further.  For a list of options available for each theme, see the