chore(rtd): Installing virtualenv and deps with uv to speed up builds (bids-standard#95)

Cuts build time in half.

Author: effigies

.readthedocs.yaml

@@ -4,10 +4,18 @@ build:
   os: ubuntu-lts-latest
   tools:
     python: latest
-
-python:
-  install:
-    - requirements: docs/requirements.txt
-
-sphinx:
-  configuration: docs/conf.py
+  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 $READTHEDOCS_VIRTUALENV_PATH/lib/python3* )/site-packages/pip.py
+      # Use a cache dir in the same mount to halve the install time
+      - VIRTUAL_ENV=$READTHEDOCS_VIRTUALENV_PATH uv pip install --cache-dir $READTHEDOCS_VIRTUALENV_PATH/../../uv_cache --upgrade sphinx
+    post_install:
+      - VIRTUAL_ENV=$READTHEDOCS_VIRTUALENV_PATH uv pip install --cache-dir $READTHEDOCS_VIRTUALENV_PATH/../../uv_cache -r docs/requirements.txt