Don't export hasjes to requirements.txt from poetry, in readthedocs g…

…eneration. (#2930)

.readthedocs.yaml

@@ -21,7 +21,7 @@ build:
     # the readthedocs environment.
     - pip install -r devtools/requirements-poetry.in
     post_install:
-    - poetry export --only=main --only=docs -o requirements.txt
+    - poetry export --only=main --only=docs --without-hashes -o requirements.txt
     - pip install --no-cache-dir -r requirements.txt
     - pip install .
     - python -c "from rdflib import Graph; print(Graph)"