Fixing (Bool | Nil) union in the from_cbor.

src/cbor/from_cbor.cr

@@ -218,7 +218,6 @@ end
 def Union.new(decoder : CBOR::Decoder)
   {% begin %}
     case decoder.current_token
-    {% if T.includes? Nil || T.includes? Bool %}
     when CBOR::Token::SimpleValueT
       # This value could be either a boolean or nil.
       value = decoder.read_simple_value
@@ -234,7 +233,6 @@ def Union.new(decoder : CBOR::Decoder)
       else
         raise "value is neither Bool or Nil"
       end
-    {% end %}
     {% if T.includes? String %}
     when CBOR::Token::StringT
       return decoder.read_string