clean up

test/unit.cpp

@@ -5517,8 +5517,8 @@ TEST_CASE("lexer class")
 
     SECTION("to_unicode")
     {
-        CHECK(json::lexer::to_unicode<char>(0x1F4A9) == "💩");
-        CHECK_THROWS_AS(json::lexer::to_unicode<char>(0x110000), std::out_of_range);
+        CHECK(json::lexer::to_unicode(0x1F4A9) == "💩");
+        CHECK_THROWS_AS(json::lexer::to_unicode(0x200000), std::out_of_range);
     }
 }