Google didnt push r28 manifest... use r27 instead (it is same version code)

Author: phhusson

build.sh

@@ -24,7 +24,7 @@ elif [ "$1" == "android-10.0" ];then
     phh="android-10.0"
 elif [ "$1" == "android-11.0" ];then
     manifest_url="https://android.googlesource.com/platform/manifest"
-    aosp="android-11.0.0_r28"
+    aosp="android-11.0.0_r27"
     phh="android-11.0"
 fi