build: suppress AGP-internal gradle deprecation warning

The only Gradle deprecation is inside AGP 9.2.1; our build scripts are clean.

Author: ajsb85

gradle.properties

@@ -3,3 +3,7 @@ org.gradle.caching=true
 android.useAndroidX=true
 android.nonTransitiveRClass=true
 kotlin.code.style=official
+# Suppress Gradle deprecation warnings. The only one emitted is internal to
+# AGP 9.2.1 (its VariantManager uses a Project object as a dependency notation);
+# our own build scripts are deprecation-free. Drop this when a newer AGP fixes it.
+org.gradle.warning.mode=none