snakeyaml 1.31 (#328)

see https://bitbucket.org/snakeyaml/snakeyaml/wiki/Changes

Author: pjfanning

yaml/pom.xml

@@ -34,7 +34,7 @@
     <dependency>
       <groupId>org.yaml</groupId>
       <artifactId>snakeyaml</artifactId>
-      <version>1.30</version>
+      <version>1.31</version>
     </dependency>
 
      <!-- and for testing need annotations; but should be available via `jackson-databind` above