Revert changing .min.max to .clamp

This library needs to compile with rustc 1.40 for some reason and .clamp
was added in 1.50, so reverting for now.

Author: tiaanl

src/color.rs

@@ -853,7 +853,8 @@ where
         component_parser
             .parse_number_or_percentage(arguments)?
             .unit_value()
-            .clamp(0.0, OPAQUE)
+            .max(0.)
+            .min(OPAQUE)
     } else {
         OPAQUE
     })
@@ -936,15 +937,17 @@ where
 
     let first_percentage = component_parser
         .parse_percentage(arguments)?
-        .clamp(0.0, 1.0);
+        .max(0.)
+        .min(1.0);
 
     if uses_commas {
         arguments.expect_comma()?;
     }
 
     let second_percentage = component_parser
         .parse_percentage(arguments)?
-        .clamp(0.0, 1.0);
+        .max(0.)
+        .min(1.0);
 
     let (red, green, blue) = to_rgb(hue, first_percentage, second_percentage);
     let red = clamp_unit_f32(red);