Fix .readthedocs.yaml

GitHub: fix mxcube#839

.readthedocs.yaml

@@ -19,10 +19,21 @@ build:
   tools:
     python: "mambaforge-22.9"
 
+#  jobs:
+#    post_create_environment:
+#      - "poetry config virtualenvs.create false"
+#    post_install:
+#      - "poetry install --only=docs,main"
+
   commands:
     - "mamba env create --file conda-environment-dev.yml"
     - "mamba run --name mxcubecore poetry install --only=docs,main"
     - "mamba run --name mxcubecore poetry run sphinx-build -T -E -b html -c ./docs/ ./docs/source/ ${READTHEDOCS_OUTPUT}/html/"
 
+# `conda.environment` is probably not used, since we have custom commands,
+# but it seems to be required (wrongly) by ReadTheDocs config file validation.
+conda:
+  environment: "conda-environment-dev.yml"
+
 
 ...  # EOF