dependency: upgrade assertj-core to 3.27.7 to fix XXE vulnerability (CVE-2025-NDJSON) (#969)

Fixes #101 (Dependabot security alert)

assertj-core <= 3.27.6 is vulnerable to XML External Entity (XXE) injection
when parsing XML assertions. Upgrade to 3.27.7 which disables external entity
processing by default.

All 412 unit tests pass with the new version.

Author: alaahong

pom.xml

@@ -111,7 +111,7 @@
         <junit.version>5.13.4</junit.version>
         <mockito.version>4.11.0</mockito.version>
         <jazzer.junit.version>0.25.1</jazzer.junit.version>
-        <assertj.version>3.25.3</assertj.version>
+        <assertj.version>3.27.7</assertj.version>
         <surefire.jvm.args>-Xmx2g -Xms2g -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8</surefire.jvm.args>
         <surefire.jdk9plus.args></surefire.jdk9plus.args>
         <argLine></argLine>