Bump greenmail from 1.5.9 to 1.5.10

Bumps [greenmail](https://github.com/greenmail-mail-test/greenmail) from 1.5.9 to 1.5.10.
- [Release notes](https://github.com/greenmail-mail-test/greenmail/releases)
- [Commits](greenmail-mail-test/greenmail@release-1.5.9...release-1.5.10)

Signed-off-by: dependabot[bot] <support@dependabot.com>

build.gradle

@@ -70,7 +70,7 @@ dependencies {
     testCompile 'junit:junit:4.12'
     testCompile 'org.hamcrest:hamcrest-core:1.3'
     testCompile 'org.mockito:mockito-core:2.28.2'
-    testCompile 'com.icegreen:greenmail:1.5.9'
+    testCompile 'com.icegreen:greenmail:1.5.10'
     testCompile 'org.slf4j:slf4j-log4j12:1.7.26'
 }