tests: Trim .nim files trailing whitespace

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

tests/enum/tenum2.nim

@@ -1,14 +1,14 @@
 # Test that enum with holes is handled correctly by case statement
 
 type
-  TEnumHole = enum 
+  TEnumHole = enum
     eA = 0,
     eB = 4,
     eC = 5
-    
+
 var
   e: TEnumHole = eB
-  
+
 case e
 of eA: echo "A"
 of eB: echo "B"