doc: Build on ReadTheDocs for PR previews

Author: effigies

.readthedocs.yaml

@@ -0,0 +1,20 @@
+version: 2
+
+build:
+  os: ubuntu-lts-latest
+  tools:
+    python: latest
+  jobs:
+    pre_create_environment:
+      - asdf plugin add uv
+      - asdf install uv latest
+      - asdf global uv latest
+      # Turn `python -m virtualenv` into `python -c pass`
+      - truncate --size 0 $( dirname $( uv python find ) )/../lib/python3*/site-packages/virtualenv/__main__.py
+    post_create_environment:
+      - uv venv $READTHEDOCS_VIRTUALENV_PATH
+      # Turn `python -m pip` into `python -c pass`
+      - truncate --size 0 $( ls -d $READTHEDOCS_VIRTUALENV_PATH/lib/python3* )/site-packages/pip.py
+    post_install:
+      # Use a cache dir in the same mount to halve the install time
+      - VIRTUAL_ENV=$READTHEDOCS_VIRTUALENV_PATH uv pip install --cache-dir $READTHEDOCS_VIRTUALENV_PATH/../../uv_cache .[doc]