put the options on a single line

Author: keewis

ci/requirements/environment.yaml

@@ -12,7 +12,5 @@ dependencies:
   - numpy
   - pip
   - pip:
-      - --pre
-      - -i https://pypi.anaconda.org/scientific-python-nightly-wheels/simple
-      - --extra-index-url https://pypi.org/simple
+      - --pre -i https://pypi.anaconda.org/scientific-python-nightly-wheels/simple --extra-index-url https://pypi.org/simple
       - xarray