Build VSoCService with SDK 28

A device whose first_shipping_api_level is 28+, all apks in the vendor
partition should be built against SDK 28+. As the first shipping api
level of cuttlefish is recently updated, VSoCService being built with
SDK 26 is causing GTS failure. (b/129744020)

Switching to 28.

Bug: 129744020
Test: m VSoCService
Change-Id: I7a83639c72864cd78ceed27ed519dc7f63ae1d7c
diff --git a/guest/monitoring/vsoc_service/Android.mk b/guest/monitoring/vsoc_service/Android.mk
index ad8ce40..2f30405 100644
--- a/guest/monitoring/vsoc_service/Android.mk
+++ b/guest/monitoring/vsoc_service/Android.mk
@@ -20,7 +20,7 @@
 LOCAL_SRC_FILES := $(call all-java-files-under, java)
 LOCAL_STATIC_JAVA_LIBRARIES := guava
 LOCAL_PACKAGE_NAME := VSoCService
-LOCAL_SDK_VERSION := 26
+LOCAL_SDK_VERSION := 28
 LOCAL_PROGUARD_FLAGS := -include build/core/proguard.flags
 LOCAL_PROGUARD_FLAG_FILES := proguard.flags
 LOCAL_VENDOR_MODULE := true