jammy-amd64-tf-a-build-next: update to CMake v3.20.0 for RMM build

Aligns the CMake version with the one used in the
`jammy-amd64-tf-a-build` Docker image. This image is a
staging fork intended for testing purposes.

Change-Id: I10877b181c4893c0741e46e432284713bfb7ca8b
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
1 file changed