sim: Use range `contains` when possible

Clippy suggests using a range with `contains` in situations where we
test if a value is within a range.

Signed-off-by: David Brown <david.brown@linaro.org>
diff --git a/sim/simflash/src/pdump.rs b/sim/simflash/src/pdump.rs
index c68aa83..6243065 100644
--- a/sim/simflash/src/pdump.rs
+++ b/sim/simflash/src/pdump.rs
@@ -34,7 +34,7 @@
             self.hex.push(' ');
         }
         self.hex.push_str(&format!(" {:02x}", ch)[..]);
-        self.ascii.push(if ch >= ' ' as u8 && ch <= '~' as u8 {
+        self.ascii.push(if (b' '..=b'~').contains(&ch) {
             ch as char
         } else {
             '.'