versions: Update firecracker to 0.21.3

Release included important security updates.

References:
firecracker-microvm/firecracker#2057
firecracker-microvm/firecracker#2177

Fixes: #3095
Depends-on: github.com/kata-containers/osbuilder#508

(cherry picked from commit 11c8c19)
Signed-off-by: Archana Shinde <archana.m.shinde@intel.com>

versions.yaml

@@ -83,7 +83,7 @@ assets:
       uscan-url: >-
         https://github.com/firecracker-microvm/firecracker/tags
         .*/v?(\d\S+)\.tar\.gz
-      version: "v0.21.1"
+      version: "v0.21.3"
 
     qemu:
       description: "VMM that uses KVM"