build-appliance-image: Update to dunfell head revision

(From OE-Core rev: c4fb7d1f0f157ffafd9f907f49ea74b93b2c1d40)

Signed-off-by: Steve Sakoman <steve@sakoman.com>

meta/recipes-core/images/build-appliance-image_15.0.0.bb

@@ -24,7 +24,7 @@ IMAGE_FSTYPES = "wic.vmdk"
 
 inherit core-image setuptools3
 
-SRCREV ?= "832b812ba827d85f718fe3e43d9ceb0fae2fed0b"
+SRCREV ?= "77442211926cbe93d60108f6df4abda3bc06b735"
 SRC_URI = "git://git.yoctoproject.org/poky;branch=dunfell \
            file://Yocto_Build_Appliance.vmx \
            file://Yocto_Build_Appliance.vmxf \