ci: Fix kas branch issue with version 4.3.2

With kas 4.3, yml files need to set a branch for a specific commit
since kas now checks whether the target branch contains the specific
commit or not. This creates an issue on meta-cassini CI since
meta-cassini-bsp triggers a CI pipeline without setting the branch
parameter dynamically. This commit adds the change to set the
branch parameter dynamically to fix this issue.

Signed-off-by: Emekcan Aras <Emekcan.Aras@arm.com>