Update to Google App Engine 1.9.88

Closes gh-10381

gradle.properties

@@ -1,5 +1,5 @@
 aspectjVersion=1.9.6
-gaeVersion=1.9.83
+gaeVersion=1.9.88
 springBootVersion=2.2.13.RELEASE
 version=5.3.12.BUILD-SNAPSHOT
 org.gradle.jvmargs=-Xmx3g -XX:MaxPermSize=2048m -XX:+HeapDumpOnOutOfMemoryError