Bump stackhpc.libvirt-vm to v1.16.3

This fixes seed/infra VM provisioning failures with libvirt 10.10.0
(packaged in Rocky Linux 9.6).

Closes-Bug: #2112628
Change-Id: Ia3cd43b3cde2474eed7fbd1fcb63ad7405b9e2f6

releasenotes/notes/bump-stackhpc-libvirt-vm-1.16.3-48680a17eeb5f632.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Bumps the ``stackhpc.libvirt-vm`` role to v1.16.3 to fix seed and infra VM
+    provisioning failures on Rocky Linux 9.6.

requirements.yml

@@ -43,7 +43,7 @@ roles:
   - src: stackhpc.libvirt-host
     version: v1.12.1
   - src: stackhpc.libvirt-vm
-    version: v1.16.2
+    version: v1.16.3
   - src: stackhpc.luks
     version: 0.4.2
   - src: stackhpc.os-ironic-state