setup: Install rsync

[Meghthedev]

• some custom roms require rsync in build, "error: rsync command not found", Installing this by default in the script fixes it

[xstefen]

Give me an example of where host rsync is necessary to build a rom

[Meghthedev]

@xstefen /bin/bash: line 1: rsync: command not found

i found this error from my list of logs, i dont remember which rom it was, as the pr as submitted a while back, but i could search the error in a telegram group for build help, and did notice that many people got that error and installing rsync fixed it, not all repos ship rsync by default, whereas some do