Test

Improve interior mutability slide #4536

Job	Run time
find-languages	4s
cargo (ubuntu-latest)	21s
cargo (macos-latest)	1m 53s
format	35s
bare-metal (src/bare-metal/alloc-example, aarch64-unknown-none)	28s
bare-metal (src/bare-metal/aps/examples, aarch64-unknown-none)	37s
bare-metal (src/bare-metal/microcontrollers/examples, thumbv7em-none-eabihf)	39s
bare-metal (src/exercises/bare-metal/compass, thumbv7em-none-eabihf)	48s
bare-metal (src/exercises/bare-metal/rtc, aarch64-unknown-none)	24s
build (bn)	2m 45s
build (da)	2m 48s
build (de)	2m 37s
build (el)	2m 24s
build (en)	2m 35s
build (es)	2m 30s
build (fa)	2m 31s
build (fr)	2m 27s
build (id)	2m 23s
build (it)	2m 27s
build (ja)	2m 28s
build (ko)	2m 24s
build (pl)	2m 31s
build (pt-BR)	2m 31s
build (ro)	2m 39s
build (ru)	2m 27s
build (tr)	2m 24s
build (uk)	2m 27s
build (zh-CN)	2m 34s
build (zh-TW)	2m 34s
	56m 15s

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