tests: Trim .nim files trailing whitespace

via OSX: find . -name '*.nim' -exec sed -i '' -E 's/[[:space:]]+$//' {} +

tests/notnil/tnotnil_in_generic.nim

@@ -9,14 +9,14 @@ type
         x: int
         ud: T
 
-proc good[T](p: A[T]) = 
+proc good[T](p: A[T]) =
     discard
 
-proc bad[T](p: A[T] not nil) = 
+proc bad[T](p: A[T] not nil) =
     discard
 
 
-proc go() = 
+proc go() =
     let s = A[int](x: 1)
 
     good(s)