tests: Trim .nim files trailing whitespace

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

tests/ambsym/tambsym2.nim

@@ -8,12 +8,12 @@ type
   TMyType = object
     len: int
     data: string
-    
+
 proc len(x: TMyType): int {.inline.} = return x.len
 
 proc x(s: TMyType, len: int) =
   writeLine(stdout, len(s))
-  
+
 var
   m: TMyType
 m.len = 7