Revert snakeyaml to 1.33 (as 2.x is not fully compatible with 1.x)

This reverts commit 6cf6da8

Author: slachiewicz

modello-plugins/modello-plugin-snakeyaml/pom.xml

@@ -24,7 +24,7 @@
     <dependency>
       <groupId>org.yaml</groupId>
       <artifactId>snakeyaml</artifactId>
-      <version>2.2</version>
+      <version>1.33</version>
     </dependency>
   </dependencies>
 </project>