Larger image size is needed during build

src/freedombone-image

@@ -544,7 +544,7 @@ if [[ $VARIANT == 'meshclient' || $VARIANT == 'meshusb' ]]; then
     fi
 
     if [ ! $IMAGE_SIZE_SPECIFIED ]; then
-        IMAGE_SIZE=6G
+        IMAGE_SIZE=7.5G
     fi
 fi