Automatic toolchain upgrade to nightly-2023-09-18

[github-actions]

Update Rust toolchain from nightly-2023-09-17 to nightly-2023-09-18 without any other source changes.
This is an automatically generated pull request. If any of the CI checks fail, manual intervention is required. In such a case, review the changes at https://github.com/rust-lang/rust from rust-lang/rust@7d9bce3 up to rust-lang/rust@203c57d. The log for this commit range is:
rust-lang/rust@203c57dbe2 Auto merge of #115334 - RalfJung:transparent-aligned-zst, r=compiler-errors
rust-lang/rust@db9c21fd94 Auto merge of #115909 - Dylan-DPC:rollup-uf96r2d, r=Dylan-DPC
rust-lang/rust@8ed1d4a02d Auto merge of #114750 - Enselic:metadata-dep-info, r=compiler-errors
rust-lang/rust@f082f1dd30 Rollup merge of #115862 - clubby789:migrate-callee-translatable, r=compiler-errors
rust-lang/rust@0c5f5b6db7 Rollup merge of #115654 - RalfJung:pass-mode-cast, r=compiler-errors
rust-lang/rust@0900712fe0 Rollup merge of #115611 - lukas-code:format!("{r#ident}"), r=compiler-errors
rust-lang/rust@6011fd4655 Rollup merge of #115477 - kellerkindt:stabilized_int_impl, r=dtolnay
rust-lang/rust@584eb696df Rollup merge of #115434 - soqb:ascii-char-manual-debug, r=dtolnay
rust-lang/rust@7cbe7fa6bf Rollup merge of #114965 - benschulz:mpsc-drop, r=dtolnay
rust-lang/rust@327e6cf55c Auto merge of #114452 - weiznich:feature/diagnostic_on_unimplemented, r=compiler-errors
rust-lang/rust@cdd182cbb2 Auto merge of #115514 - onur-ozkan:bootstrap-codebase-improvements, r=albertlarsan68
rust-lang/rust@3ecc563628 Auto merge of #113748 - clarfonthey:ip-step, r=dtolnay
rust-lang/rust@9971008b8d micro-level optimizations for bootstrap
rust-lang/rust@12b1784b0b update the beginning part of bootstrap/README.md
rust-lang/rust@a09c1f85f1 Auto merge of #115782 - a1phyr:improve_pad_adapter, r=dtolnay
rust-lang/rust@d7229c479c Auto merge of #113753 - dvdsk:master, r=dtolnay
rust-lang/rust@90348db550 create helper module to be embedded for the bootstrap binaries
rust-lang/rust@8184c9c50d impl Step for IP addresses
rust-lang/rust@8696ee8b09 Migrate 'missing fn lang items' diagnostic
rust-lang/rust@cb9f666fdf Migrate 'invalid callee' diagnostic
rust-lang/rust@b40f11c8a9 Migrate 'rust-call incorrect arguments' diagnostic
rust-lang/rust@9edeb19f96 Allow internal untranslatable diagnostic
rust-lang/rust@6e2adbf6a3 Migrate 'explicit destructor call' diagnostic
rust-lang/rust@3ee65c28e9 cannot have Direct for unsized types
rust-lang/rust@29a4b7b971 fix gcc, cranelift build
rust-lang/rust@89139d4c46 clarify PassMode::Indirect as well
rust-lang/rust@7740476a43 explain PassMode::Cast
rust-lang/rust@5b8a7a0917 #[diagnostic::on_unimplemented] without filters
rust-lang/rust@814f4f6f52 Improve PadAdapter::write_char
rust-lang/rust@d990eee0c8 add diagnostic for raw identifiers in format string
rust-lang/rust@04d81ba153 Make .rmeta file in dep-info have correct name (lib prefix)
rust-lang/rust@ad54426945 Stabilize the Saturating type (saturating_int_impl, gh-87920)
rust-lang/rust@0eb41335e2 Unimpl Shl, ShlAssign, Shr and ShrAssign for Saturating
rust-lang/rust@9c0e5ebf65 fix Debug impl for AsciiChar
rust-lang/rust@a6ccd265e6 mark error code as removed
rust-lang/rust@9dd682803f repr(transparent): it's fine if the one non-1-ZST field is a ZST
rust-lang/rust@a38ea96825 Remove Drop impl of mpsc Receiver and (Sync)Sender
rust-lang/rust@4cf66f0b09 adds crate attribute to examples so they compile
rust-lang/rust@bd70b639fd fix examples add tracking issue
rust-lang/rust@77844f015f fixes sleep_until examples
rust-lang/rust@4854fc9646 Adds thread::sleep_until, tracking issue TODO