Move to CMake 3.20.0.
At the Toolchain WG it was decided to move to CMake 3.20.0.
The main reason for increasing CMake version is better toolchain
support.
Better toolchain support is added in the following CMake versions:
- armclang, CMake 3.15
- Intel oneAPI, CMake 3.20
- IAR, CMake 3.15 and 3.20
Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>
Add the nanopb library and generator tools as a module.
Nanopb is a small code-size Protocol Buffers implementation in ansi C.
It is especially suitable for use in microcontrollers,
but fits any memory restricted system.
Nanopb home: https://jpa.kapsi.fi/nanopb/
Signed-off-by: Pieter De Gendt <pieter.degendt@basalte.be>