ttrpc-codegen: Fix clippy error manual_find

Got:

error: manual implementation of `Iterator::find`
   --> src/parser.rs:354:9
    |
354 | /         for c in alphabet.chars() {
355 | |             if self.next_char_if_eq(c) {
356 | |                 return Some(c);
357 | |             }
358 | |         }
359 | |         None
    | |____________^ help: replace with an iterator: `alphabet.chars().find(|&c| self.next_char_if_eq(c))`
    |
    = note: `-D clippy::manual-find` implied by `-D warnings`
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#manual_find

This commit will fix the problem.

Signed-off-by: Tim Zhang <[email protected]>

ttrpc-codegen/src/parser.rs

@@ -351,12 +351,7 @@ impl<'a> Lexer<'a> {
     }
 
     fn next_char_if_in(&mut self, alphabet: &str) -> Option<char> {
-        for c in alphabet.chars() {
-            if self.next_char_if_eq(c) {
-                return Some(c);
-            }
-        }
-        None
+        alphabet.chars().find(|&c| self.next_char_if_eq(c))
     }
 
     fn next_char_expect_eq(&mut self, expect: char) -> ParserResult<()> {