Bump conda-incubator/setup-miniconda from 2 to 3 (GraphBLAS#115)

Author: dependabot[bot]

.github/workflows/test.yml

@@ -25,7 +25,7 @@ jobs:
       with:
         fetch-depth: 0
     - name: Conda
-      uses: conda-incubator/setup-miniconda@v2
+      uses: conda-incubator/setup-miniconda@v3
       with:
         auto-update-conda: true
         python-version: ${{ matrix.python-version }}