der_derive: add workaround for `syn` v2.0.73 #3153

Job	Run time
build (1.72.0, thumbv7em-none-eabi)	54s
minimal-versions	0s
build (1.72.0, wasm32-unknown-unknown)	50s
test (1.72.0)	4m 19s
build (stable, thumbv7em-none-eabi)	49s
test (stable)	4m 19s
build (stable, wasm32-unknown-unknown)	46s
	11m 57s

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