Pull alphas when building nightlies

ci/build_wheel.sh

@@ -12,6 +12,17 @@ commit=$(git rev-parse HEAD)
 echo "${version}" | tr -d '"' > VERSION
 sed -i "/^__git_commit__/ s/= .*/= \"${commit}\"/g" "dask_cuda/_version.py"
 
+# For nightlies we want to ensure that we're pulling in alphas as well. The
+# easiest way to do so is to augment the spec with a constraint containing a
+# min alpha version that doesn't affect the version bounds but does allow usage
+# of alpha versions for that dependency without --pre
+alpha_spec=''
+if ! rapids-is-release-build; then
+        alpha_spec=',>=0.0.0a0'
+fi
+
+sed -r -i "s/rapids-dask-dependency==(.*)\"/rapids-dask-dependency==\1${alpha_spec}\"/g" pyproject.toml
+
 python -m pip wheel . -w dist -vvv --no-deps --disable-pip-version-check
 
 RAPIDS_PY_WHEEL_NAME="dask-cuda" rapids-upload-wheels-to-s3 dist