Add clippy and rustfmt to the diff check

These repos are explicitly skipped by r-l/rust's `rustfmt.toml` so i'm
adding them to include them in the diff check.

Author: ytmimi

check_diff/src/main.rs

@@ -19,7 +19,9 @@ const REPOS: &[&str] = &[
     "https://github.com/rust-lang/packed_simd.git",
     "https://github.com/rust-lang/rust-analyzer.git",
     "https://github.com/rust-lang/rust-bindgen.git",
+    "https://github.com/rust-lang/rust-clippy.git",
     "https://github.com/rust-lang/rust-semverver.git",
+    "https://github.com/rust-lang/rustfmt.git",
     "https://github.com/rust-lang/rust.git",
     "https://github.com/rust-lang/rustlings.git",
     "https://github.com/rust-lang/rustup.git",