[build] bump version number to 1.4alpha8
[build] bump version number to 1.4alpha8

jjffryan/pymtl,cornell-brg/pymtl,cfelton/pymtl,Glyfina-Fernando/pymtl,jjffryan/pymtl,tj93/pymtl,jck/pymtl,cfelton/pymtl,cfelton/pymtl,12yujim/pymtl,jck/pymtl,Glyfina-Fernando/pymtl,tj93/pymtl,12yujim/pymtl,cornell-brg/pymtl,jjffryan/pymtl,Glyfina-Fernando/pymtl,cornell-brg/pymtl,12yujim/pymtl,jck/pymtl,tj93/pymtl