Bump android animalsniffer signature to API 21

This should have been done as part of 2b4f649

Author: ejona86

gradle/libs.versions.toml

@@ -97,7 +97,7 @@ protobuf-javalite = { module = "com.google.protobuf:protobuf-javalite", version.
 protobuf-protoc = { module = "com.google.protobuf:protoc", version.ref = "protobuf" }
 re2j = "com.google.re2j:re2j:1.7"
 robolectric = "org.robolectric:robolectric:4.13"
-signature-android = "net.sf.androidscents.signature:android-api-level-19:4.4.2_r4"
+signature-android = "net.sf.androidscents.signature:android-api-level-21:5.0.1_r2"
 signature-java = "org.codehaus.mojo.signature:java18:1.0"
 # 11.0.0+ require Java 17+
 tomcat-embed-core = "org.apache.tomcat.embed:tomcat-embed-core:10.1.31"