Put back deprecation path for SomeReal

was wrongly deleted in c7298561c1

lib/system.nim

@@ -106,6 +106,8 @@ type
   SomeNumber* = SomeInteger|SomeFloat
     ## type class matching all number types
 
+{.deprecated: [SomeReal: SomeFloat].}
+
 proc defined*(x: untyped): bool {.magic: "Defined", noSideEffect, compileTime.}
   ## Special compile-time procedure that checks whether `x` is
   ## defined.