Automatic toolchain upgrade to nightly-2025-09-28

[github-actions]

Update Rust toolchain from nightly-2025-09-27 to nightly-2025-09-28 without any other source changes.

[github-actions]

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@54a8a1d up to
rust-lang/rust@4082d6a. The log
for this commit range is:

https://github.com/rust-lang/rust/commit/4082d6a3f0 Auto merge of #146927 - Kobzol:install-clif, r=jieyouxu

rust-lang/rust@c0ee51f07d Auto merge of #138907 - GuillaumeGomez:rfc-3631, r=fmease,camelid,Manishearth,lolbinarycat
rust-lang/rust@ade84871f7 Auto merge of #146829 - cjgillot:jump-threading-loop-dominator, r=dianqk
rust-lang/rust@6cccea8731 Remove doc_auto_cfg feature as well
rust-lang/rust@9362ab549f Improve code and fix typo
rust-lang/rust@653e1036ed Apply first review round suggestions
rust-lang/rust@77885fef2c Improve code comments and extend tests for doc_cfg feature
rust-lang/rust@ef8b2a26ca Correctly handle target_feature in rustdoc cfg
rust-lang/rust@6fecff45d9 Fix tests/rustdoc/target-feature.rs test by adding missing #![feature(doc_cfg)]
rust-lang/rust@254a2139f6 Remove cfg(bootstrap) for doc_cfg feature following #141925
rust-lang/rust@ec00723ba1 Fix autodiff feature activation
rust-lang/rust@a7ed9bf6c7 fmt
rust-lang/rust@fccba2c341 Remove doc_cfg_hide feature
rust-lang/rust@553308b115 Improve code and better check doc(cfg(...)) attributes
rust-lang/rust@1561efe41a Add code documentation, improve code and improve error message
rust-lang/rust@c06a076634 Put back the doc_cfg code behind a nightly feature
rust-lang/rust@ed05315867 Rename CfgInfo::doc_auto_cfg_active into auto_cfg_active
rust-lang/rust@bb34332858 Update book for doc_cfg feature
rust-lang/rust@d6ba93a3fe Remove doc_cfg related content from rustdoc book unstable features chapter
rust-lang/rust@18df897221 Remove ui test for doc_cfg feature gate
rust-lang/rust@4847eaf6d2 Remove useless code in propagate_doc_cfg.rs
rust-lang/rust@63aefe0737 Strenghten checks for doc(auto_cfg(show/hide)) attributes
rust-lang/rust@2d82c99f1e Add "global" rustdoc test for RFC 3631
rust-lang/rust@6537278e11 Update rustdoc tests
rust-lang/rust@7c00bccd3b Implement RFC 3631
rust-lang/rust@959b450747 Auto merge of #146636 - Mark-Simulacrum:bootstrap-bump, r=jieyouxu
rust-lang/rust@e131842222 Auto merge of #147074 - matthiaskrgr:rollup-sm3owsd, r=matthiaskrgr
rust-lang/rust@54669d7db4 Bump stage0
rust-lang/rust@201f299ef6 Apply cfg(bootstrap) replacement
rust-lang/rust@4e9716fbc5 Update CURRENT_RUSTC_VERSION post-bump