Adjust snakeyaml version

Version 1.21 of snakeyaml is breaking junits in policy/pap.

Change-Id: Ic7716c49f7797b8461846f1c61717c620471a2b5
Issue-ID: POLICY-1542
Signed-off-by: Jim Hahn <jrh3@att.com>
diff --git a/pom.xml b/pom.xml
index 5a22b52..3d18359 100644
--- a/pom.xml
+++ b/pom.xml
@@ -91,7 +91,7 @@
         <dependency>
             <groupId>org.yaml</groupId>
             <artifactId>snakeyaml</artifactId>
-            <version>1.21</version>
+            <version>1.18</version>
         </dependency>
 
         <dependency>