[FLUME-3472] fix vulnerability CVE 2020-1938 caused by tomcat-embed-core

Author: nikita15p

flume-parent/pom.xml

@@ -895,6 +895,11 @@ limitations under the License.
         </exclusions>
       </dependency>
 
+      <dependency>
+        <groupId>org.apache.tomcat.embed</groupId>
+        <artifactId>tomcat-embed-core</artifactId>
+        <version>9.0.68</version>
+      </dependency>
       <dependency>
         <groupId>org.apache.thrift</groupId>
         <artifactId>libthrift</artifactId>