Merge pull request #236 from browserup/dependabot/gradle/log4jVersion-2.13.1

Bump log4jVersion from 2.13.0 to 2.13.1

Author: dpowell

build.gradle

@@ -36,7 +36,7 @@ subprojects {
         bcpVersion = '1.64'
         jacksonVersion = '2.10.2'
         jettyVersion = '9.4.26.v20200117'
-        log4jVersion = '2.13.0'
+        log4jVersion = '2.13.1'
         slf4jVersion = '1.7.30'
     }