fix sphinx builds

documentation/.readthedocs.yaml

+# Read the Docs configuration file for Sphinx projects
+
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html for details
+
+
+# Required
+
+version: 2
+
+
+# Set the OS, Python version and other tools you might need
+
+build:
+
+  os: ubuntu-22.04
+
+  tools:
+
+    python: "3.12"
+
+    # You can also specify other tool versions:
+
+    # nodejs: "20"
+
+    # rust: "1.70"
+
+    # golang: "1.20"
+
+
+# Build documentation in the "docs/" directory with Sphinx
+
+sphinx:
+
+  configuration: docs/conf.py
+
+  # You can configure Sphinx to use a different builder, for instance use the dirhtml builder for simpler URLs
+
+  # builder: "dirhtml"
+
+  # Fail on all warnings to avoid broken references
+
+  # fail_on_warning: true
+
+
+# Optionally build your docs in additional formats such as PDF and ePub
+
+ formats:
+
+   - pdf
+
+#   - epub
+
+
+# Optional but recommended, declare the Python requirements required
+
+# to build your documentation
+
+# See https://docs.readthedocs.io/en/stable/guides/reproducible-builds.html
+
+# python:
+
+#   install:
+
+#     - requirements: docs/requirements.txt
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