Update config.yml

Author: LiamConnors

Diff for: .circleci/config.yml

@@ -370,7 +370,7 @@ jobs:
       - run:
           name: Create conda environment
           command: |
-            conda create -n env --yes python=3.9 conda-build conda-verify
+            conda create -n env --yes python=3.9 conda-build=3.28.4 conda-verify
             conda install -n env -c conda-forge jupyterlab=3 nodejs=16
             conda init bash
             mkdir output