.pytool: Add required submodule for JsonLib

.pytool: Add required submodule for JsonLib

Open source project jansson is leveraged by edk2 JsonLib.
Add jansson to the required submodule in CiSettings.py.

Signed-off-by: Abner Chang <abner.chang@hpe.com>
Cc: Sean Brogan <sean.brogan@microsoft.com>
Cc: Bret Barkelew <Bret.Barkelew@microsoft.com>
Cc: Nickle Wang <nickle.wang@hpe.com>
Cc: Peter O'Hanley <peter.ohanley@hpe.com>
Reviewed-by: Bret Barkelew <Bret.Barkelew@microsoft.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>