HDDS-949. Update Ratis to 0.4.0-a8c4ca0-SNAPSHOT.

Contributed by Xiaoyu Yao.

hadoop-hdds/pom.xml

@@ -46,7 +46,7 @@ http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <hdds.version>0.4.0-SNAPSHOT</hdds.version>
 
     <!-- Apache Ratis version -->
-    <ratis.version>0.4.0-3b0be02-SNAPSHOT</ratis.version>
+    <ratis.version>0.4.0-a8c4ca0-SNAPSHOT</ratis.version>
 
     <bouncycastle.version>1.60</bouncycastle.version>
 

hadoop-ozone/pom.xml

@@ -33,7 +33,7 @@ http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <hadoop.version>3.2.1-SNAPSHOT</hadoop.version>
     <hdds.version>0.4.0-SNAPSHOT</hdds.version>
     <ozone.version>0.4.0-SNAPSHOT</ozone.version>
-    <ratis.version>0.4.0-3b0be02-SNAPSHOT</ratis.version>
+    <ratis.version>0.4.0-a8c4ca0-SNAPSHOT</ratis.version>
     <bouncycastle.version>1.60</bouncycastle.version>
     <ozone.release>Badlands</ozone.release>
     <declared.ozone.version>${ozone.version}</declared.ozone.version>