Adding @TypeSystemReference for FormatNode

Author: ppisl

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/floats/FloatBuiltins.java

@@ -131,6 +131,7 @@ abstract static class ReprNode extends StrNode {
 
     @Builtin(name = __FORMAT__, fixedNumOfPositionalArgs = 2)
     @GenerateNodeFactory
+    @TypeSystemReference(PythonArithmeticTypes.class)
     abstract static class FormatNode extends PythonBinaryBuiltinNode {
 
         @Specialization