🔧 Force RTD to use Python 3.8

RTD used Python 3.7 for some reason and the Archiefbeheercomponent requires 3.8 at minimum.

.readthedocs.yaml

@@ -0,0 +1,20 @@
+# Read the Docs configuration file
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+# Required
+version: 2
+
+# Set the version of Python and other tools you might need
+build:
+  os: ubuntu-20.04
+  tools:
+    python: "3.8"
+
+# Build documentation in the docs/ directory with Sphinx
+sphinx:
+   configuration: doc/conf.py
+
+# Optionally declare the Python requirements required to build your docs
+python:
+   install:
+   - requirements: requirements/dev.txt