fix: readthedocs failure with poetry 1.8 (#2744)

* chore: set poetry to 1.8.0

* build: debug readthedocs config

* build: update readthedocs config to use poetry export

* build: remove bad command

* build: poetry export add -o flag

* build: add pip install .

.readthedocs.yaml

@@ -21,9 +21,10 @@ build:
     # the readthedocs environment.
     - pip install -r devtools/requirements-poetry.in
     post_install:
-    - poetry config virtualenvs.create false
-    - poetry install --only=main --only=docs --extras=html
-    - poetry env info
+    - poetry export --only=main --only=docs --extras=html -o requirements.txt
+    - pip install --no-cache-dir -r requirements.txt
+    - pip install .
+    - python -c "from rdflib import Graph; print(Graph)"
 
 sphinx:
   fail_on_warning: true

devtools/requirements-poetry.in

@@ -1,3 +1,3 @@
 # Fixing this here as readthedocs can't use the compiled requirements-poetry.txt
 # due to conflicts.
-poetry==1.7.1
+poetry==1.8.0