tests: Trim .nim files trailing whitespace

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

tests/misc/tnot.nim

@@ -5,10 +5,10 @@ discard """
 """
 # BUG: following compiles, but should not:
 
-proc nodeOfDegree(x: int): bool = 
+proc nodeOfDegree(x: int): bool =
   result = false
 
-proc main = 
+proc main =
   for j in 0..2:
     for i in 0..10:
       if not nodeOfDegree(1) >= 0: #ERROR_MSG type mismatch