Etar: Bump gradle-generatebp to v1.9

Change-Id: Ie9e549e2dea242ca307a3f2b7b7958975e023666
diff --git a/app/generatebp.gradle.kts b/app/generatebp.gradle.kts
index f6145f5..41b161e 100644
--- a/app/generatebp.gradle.kts
+++ b/app/generatebp.gradle.kts
@@ -8,7 +8,7 @@
 
 buildscript {
     repositories {
-        maven("https://raw.githubusercontent.com/lineage-next/gradle-generatebp/v1.3/.m2")
+        maven("https://raw.githubusercontent.com/lineage-next/gradle-generatebp/v1.9/.m2")
     }
 
     dependencies {