Revert "Compile to JVM target 17"

Revert submission 22894938-compile-to-jvm-target-17

Reason for revert: Google3 consumes some artifacts that need to target 11 (see b/284344368)

Reverted changes: /q/submissionid:22894938-compile-to-jvm-target-17

Change-Id: I4c5e256e2c0d6f5e9a107cbfb8f87f9fc69a0b2a
diff --git a/build.gradle b/build.gradle
index c5d10d7..23de8dc 100644
--- a/build.gradle
+++ b/build.gradle
@@ -2,7 +2,7 @@
 
 apply plugin: 'java'
 
-sourceCompatibility = '17'
+sourceCompatibility = '11'
 
 repositories {
     jcenter()