clippy: fix cast_lossless lint

Cargo.toml

@@ -157,7 +157,6 @@ manual_assert = "allow"                      # 2
 ignore_without_reason = "allow"              # 2
 if_not_else = "allow"                        # 2
 format_push_string = "allow"                 # 2
-cast_lossless = "allow"                      # 2
 should_panic_without_expect = "allow"        # 1
 many_single_char_names = "allow"             # 1
 comparison_chain = "allow"

src/sed/delimited_parser.rs

@@ -77,7 +77,7 @@ fn create_control_char(x: char) -> Option<char> {
     let c = x.to_ascii_uppercase();
 
     let transformed = (c as u8) ^ 0x40;
-    char::from_u32(transformed as u32)
+    char::from_u32(u32::from(transformed))
 }
 
 /// Parse a character escape valid in all contexts (RE pattern, substitution,