Use more efficient bool to int conversion

sandbox/darren/just_a_box.css

@@ -2,5 +2,5 @@
     height: 50%;
     width: 50%;
     align: center middle;
-    background: blue;
+    background: green;
 }

src/textual/css/styles.py

@@ -530,7 +530,11 @@ class Styles(StylesBase):
         rules = [
             (
                 rule_name,
-                (int(not is_widget_rule), int(is_important(rule_name)), *specificity),
+                (
+                    0 if is_widget_rule else 1,
+                    1 if is_important(rule_name) else 0,
+                    *specificity,
+                ),
                 rule_value,
             )
             for rule_name, rule_value in self._rules.items()