tests: Trim .nim files trailing whitespace

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

tests/array/tarray3.nim

@@ -2,9 +2,9 @@ discard """
   file: "tarray3.nim"
   output: "3"
 """
-# simple check for two dimensional arrays
+# simple check for two dimensional arrays
 
-const  
+const
   myData = [[1,2,3], [4, 5, 6]]
 
 echo myData[0][2] #OUT 3