bsp:stm32：Add reminder for missing dependency packages #6066

Job	Run time
generate-matrix	7s
RTduino_Arduino Libraries (STM32F412 Nucleo)	7m 54s
RT-Thread Online Packages (STM32F407 RT-Spark)	5m 11s
stm32f0_f1	4m 59s
stm32l4	8m 10s
stm32_f7_g0_h7_mp15_u5_h5_wb5	7m 48s
llvm-arm	3m 54s
stm32_f2_f4	9m 30s
collect-artifacts	0s
	47m 33s

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