fix: Suppress errors when including the ci.mk

The test-framework clones the bao-hypervisor but does not need to initialize
all the submodules. When the ci in not cloned, the Makefile issues an error
because it cannot find the ci.mk.

Signed-off-by: Miguel Silva <miguelafsilva5@gmail.com>

Author: miguelafsilva5

Makefile

@@ -47,7 +47,7 @@ scripts_dir:=$(cur_dir)/scripts
 ci_dir:=$(cur_dir)/ci
 src_dirs:=
 
-include $(ci_dir)/ci.mk
+-include $(ci_dir)/ci.mk
 
 targets:=$(MAKECMDGOALS)
 ifeq ($(targets),)