TIdy up some comments,

MANIFEST.in

@@ -10,5 +10,5 @@ recursive-include tools *
 recursive-include user_libs *
 recursive-include user_models *
 
-# exclude what we don't want to include
+# Exclude what we don't want to include
 global-exclude *.DS_Store

conda_env.yml

@@ -3,7 +3,7 @@
 
 name: gprMax-devel
 dependencies:
-- python>3.6
+- python>3.7
 - colorama
 - cython
 - h5py