added test for tensor of submodule

Author: Devlin-Mallory

M2/Macaulay2/tests/normal/ringmap8.m2

@@ -0,0 +1,5 @@
+S = QQ[x]
+M = image matrix{{x}}
+R = S/x
+assert(tensor(map(R, S), M) != 0)
+assert(isFreeModule tensor(map(R, S), M))