Added an extra test for the isogram exercise. This ensures that implementations that use a simple regex replace of non-word characters will not pass.
Added an extra test for the isogram exercise. This ensures that implementations that use a simple regex replace of non-word characters will not pass.

jmluy/x-common,Vankog/problem-specifications,exercism/x-common,jmluy/x-common,rpottsoh/x-common,petertseng/x-common,ErikSchierboom/x-common,petertseng/x-common,ErikSchierboom/x-common,rpottsoh/x-common,Vankog/problem-specifications,jmluy/x-common,kgengler/x-common,kgengler/x-common,exercism/x-common