Added specific conda environment for macOS to get around MKL threading bug - use OpenBLAS instead.

conda_env_macOS.yml

@@ -1,7 +1,7 @@
 # This file may be used to create a conda environment using:
 # $ conda create --name gprMax --file <this file>
 
-name: gprMax
+name: gprMax_openblas
 dependencies:
 - python>3.6
 - blas=*=openblas