Run nightly Clippy over the Ruff repo (#5670)

## Summary

This is the result of running `cargo +nightly clippy --workspace
--all-targets --all-features -- -D warnings` and fixing all violations.
Just wanted to see if there were any interesting new checks on nightly
👀

crates/ruff_python_ast/src/source_code/indexer.rs

@@ -201,7 +201,7 @@ if True:
             ]
         );
 
-        let contents = r#"
+        let contents = r"
 x = 1; import sys
 import os
 
@@ -215,7 +215,7 @@ if True:
 
 x = 1; \
 import os
-"#
+"
         .trim();
         let lxr: Vec<LexResult> = lexer::lex(contents, Mode::Module).collect();
         let indexer = Indexer::from_tokens(lxr.as_slice(), &Locator::new(contents));