build(deps-dev): bump com.icegreen:greenmail-junit4 from 2.1.7 to 2.1.8

Bumps [com.icegreen:greenmail-junit4](https://github.com/greenmail-mail-test/greenmail) from 2.1.7 to 2.1.8.
- [Release notes](https://github.com/greenmail-mail-test/greenmail/releases)
- [Commits](greenmail-mail-test/greenmail@release-2.1.7...release-2.1.8)

---
updated-dependencies:
- dependency-name: com.icegreen:greenmail-junit4
  dependency-version: 2.1.8
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

pom.xml

@@ -100,7 +100,7 @@
         <lib.owasp-rr-calculator.version>1.0.1</lib.owasp-rr-calculator.version>
         <lib.cyclonedx-java.version>11.0.1</lib.cyclonedx-java.version>
         <lib.jakarta-validation.version>3.0.2</lib.jakarta-validation.version>
-        <lib.greenmail.version>2.1.7</lib.greenmail.version>
+        <lib.greenmail.version>2.1.8</lib.greenmail.version>
         <lib.json-java.version>20250107</lib.json-java.version>
         <lib.json-unit.version>4.1.1</lib.json-unit.version>
         <lib.junit.version>4.13.2</lib.junit.version>