Switch a few core plugins to the new api
diff --git a/pom.xml b/pom.xml
index e3872db..eeb5d2f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -146,7 +146,7 @@
       <plugin>
         <groupId>org.codehaus.mojo</groupId>
         <artifactId>animal-sniffer-maven-plugin</artifactId>
-        <version>1.20</version>
+        <version>1.21</version>
       </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>