bsp:stm32：Add reminder for missing dependency packages #6121

Job	Run time
generate-matrix	11s
RT-Thread Online Packages (STM32F407 RT-Spark)	5m 23s
stm32f0_f1	4m 40s
llvm-arm	3m 23s
stm32l4	8m 54s
stm32_f7_g0_h7_mp15_u5_h5_wb5	6m 48s
stm32_f2_f4	11m 7s
collect-artifacts	0s
	40m 26s

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