Rollup merge of #89814 - jkugelman:must-use-string-transforms-typo, r=joshtriplett
Rollup merge of #89814 - jkugelman:must-use-string-transforms-typo, r=joshtriplett

Fix uppercase/lowercase error

Fix https://github.com/rust-lang/rust/pull/89694#discussion_r726829890

r? ````@joshtriplett````

aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust