Trouble compiling with vscode + platformio + STM32F407ZG

[i-make-robots]

Hello! Thank you for all your hard work.

I am trying to use this library in platformio with the SKR PRO 1.2 (STM32F407ZG). I'm including
arduino-libraries/Servo@^1.1.7 in platformio. At first I get

#error "This library only supports boards with an AVR, SAM, SAMD, NRF52 or STM32F4 processor."

I see that it may require #define ARDUINO_ARCH_STM32F4. I tried to define this myself and then I get

.pio\libdeps\BIGTREE_SKR_PRO-Sixi3\Servo\src/stm32f4/ServoTimers.h:34:10: fatal error: types.h: No such file or directory

FWIW my firmware is https://github.com/marginallyclever/makelangelo-firmware and I'm on the Sixi3 branch.
If you have some idea what I'm doing wrong, please let me know.