cloud-init: switch branch to main
cloud-init: switch branch to main

Cloud-init has removed the master branch, and has switched
to using main.

So we adjust our recipe accordingly to avoid fetcher errors.

Signed-off-by: Bruce Ashfield <284cc737d174a260eec2a2a6324a304f84b1ae0f@gmail.com>

lgirdk/meta-virtualization,lgirdk/meta-virtualization,lgirdk/meta-virtualization,lgirdk/meta-virtualization,lgirdk/meta-virtualization