Update dependency org.yaml:snakeyaml to v2.6

Author: renovate[bot]

pom.xml

@@ -66,7 +66,7 @@
     <dependency>
       <groupId>org.yaml</groupId>
       <artifactId>snakeyaml</artifactId>
-      <version>2.4</version>
+      <version>2.6</version>
     </dependency>
     <dependency>
       <groupId>com.jcabi</groupId>