tests: Trim .nim files trailing whitespace

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

tests/proc/tnestprc.nim

@@ -4,12 +4,12 @@ discard """
 """
 # Test nested procs without closures
 
-proc Add3(x: int): int = 
-  proc add(x, y: int): int {.noconv.} = 
+proc Add3(x: int): int =
+  proc add(x, y: int): int {.noconv.} =
     result = x + y
-    
+
   result = add(x, 3)
-  
+
 echo Add3(7) #OUT 10