Remove default channel when building conda package in CI

Author: ndgrigorian

.github/workflows/conda-package.yml

@@ -145,6 +145,7 @@ jobs:
           miniforge-version: latest
           activate-environment: build
           channels: conda-forge
+          conda-remove-defaults: true
           python-version: ${{ matrix.python }}
 
       - name: Cache conda packages
@@ -208,7 +209,8 @@ jobs:
           miniforge-variant: Miniforge3
           miniforge-version: latest
           activate-environment: mkl_umath_test
-          channels: conda-forge,nodefaults
+          channels: conda-forge
+          conda-remove-defaults: true
           python-version: ${{ matrix.python }}
 
       - name: Install conda-index