Downgrade DnsJava

DnsJava 3.x crashes on devices without java.nio.file.Paths, which
desugar doesn't help with. Until minSdk is 26-ish (Android O), we should
continue using the 2.x version.

gradle/libs.versions.toml

@@ -14,7 +14,7 @@ anvil = "0.4.0"
 coroutinesVersion = "1.9.0"
 crashlytics = "3.0.2"
 daggerVersion = "2.52"
-dnsjavaVersion = "3.6.2"
+dnsjavaVersion = "2.1.9"
 errorprone = "4.1.0"
 errorproneCoreVersion = "2.36.0"
 googleServices = "4.4.2"