fix(rust): make rust doc tests not run with nightly #2618

Job	Run time
ci / discover	15s
ci / check / .+check-bash	29s
ci / check / .+check-markdown	34s
ci / check / .+check-spelling	28s
ci / check / ./examples/go+check	34s
ci / check / ./examples/postgresql+check	37s
ci / check / ./examples/python+check	41s
ci / check / ./examples/rust+check	1m 2s
ci / check / ./utilities/cql-to-d2+check	33s
ci / check / ./utilities/earthly-cache-watcher+check	33s
ci / check / ./utilities/fetcher+check	34s
ci / check / ./utilities/jorm-metrics-server+check	28s
ci / build / ./examples/go+build	26s
ci / build / ./examples/postgresql+build	4m 15s
ci / build / ./examples/rust+build	1m 1s
ci / build / ./examples/wasm/c+build	30s
ci / build / ./utilities/fetcher+build	27s
ci / build / ./utilities/jorm-metrics-server+build	31s
ci / package	0s
ci / test	0s
ci / docs	0s
ci / release	0s
ci / final	0s
ci / deploy	0s
	13m 58s

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