revert changes to inheritance diagram settings

.readthedocs.yaml

@@ -17,15 +17,15 @@ build:
 
 # Build documentation in the docs/ directory with Sphinx
 sphinx:
-   configuration: docs/conf.py
+  configuration: docs/conf.py
 
 # Optionally build your docs in additional formats such as PDF
 # formats:
 #    - pdf
 
 # Optionally declare the Python requirements required to build your docs
 python:
-   install:
-   - requirements: requirements-docs.txt
-     method: pip
-     path: .
+  install:
+    - requirements: requirements-docs.txt
+    - method: pip
+      path: .

docs/conf.py

@@ -33,15 +33,14 @@
 # ones.
 extensions = [
     "sphinx.ext.autodoc",
+    "sphinx.ext.graphviz",
     "sphinx.ext.inheritance_diagram",
     "sphinx.ext.intersphinx",
     "sphinx_autodoc_typehints",
     "sphinx_rtd_theme",
 ]
 
 intersphinx_mapping = {
-    "apispec": ("https://apispec.readthedocs.io/en/latest/", None),
-    "marshmallow": ("https://marshmallow.readthedocs.io/en/stable/", None),
     "pint": ("https://pint.readthedocs.io/en/stable/", None),
     "python": ("https://docs.python.org/3", None),
     "sympy": ("https://docs.sympy.org/latest/", None),