remove MKLROOT from build_pip

Author: ndgrigorian

.github/workflows/build_pip.yaml

@@ -53,8 +53,6 @@ jobs:
         run: |
           pip install --no-cache-dir meson-python ninja cmake cython
           pip install --no-cache-dir numpy ${{ matrix.use_pre }}
-          echo "CONDA_PREFFIX is '${CONDA_PREFIX}'"
-          export MKLROOT=${CONDA_PREFIX}
           pip install -e ".[test]" --no-build-isolation --verbose
           pip list
           python -m pytest -v mkl_fft/tests