Add requirements for ReadTheDocs

Requirements are needed to generate the documentation. Pipfile is not supported
yet (see readthedocs/readthedocs.org#3181).

We also have to mock gi because ReadTheDocs don’t provide the packages needed
to install pygobject.

docs/source/conf.py

@@ -69,3 +69,8 @@
 # alphabetical (value 'alphabetical'), by member type (value 'groupwise') or by
 # source order (value 'bysource'). The default is alphabetical.
 autodoc_member_order = 'bysource'
+
+# This value contains a list of modules to be mocked up. This is useful when
+# some external dependencies are not met at build time and break the building
+# process.
+autodoc_mock_imports = ['gi']

readthedocs.yml

@@ -0,0 +1,10 @@
+# .readthedocs.yml
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+# Required
+version: 2
+
+python:
+  install:
+    - requirements: requirements.readthedocs.txt

requirements.readthedocs.txt

@@ -0,0 +1,7 @@
+alembic
+psycopg2
+pydantic
+redis
+requests
+sqlalchemy
+toml