build: update maven-compiler-plugin to 3.8.1

Changelogs:
- https://mail-archives.apache.org/mod_mbox/maven-announce/201807.mbox/%3C20180729204015.DBA2918784%40minotaur.apache.org%3E
- https://mail-archives.apache.org/mod_mbox/maven-dev/201905.mbox/%[email protected]%3E

Fix #1175

Author: php-coder

pom.xml

@@ -519,7 +519,7 @@
 		<commons-lang3.version>3.8</commons-lang3.version>
 
 		<commons.text.version>1.4</commons.text.version>
-		<compiler.plugin.version>3.7.0</compiler.plugin.version>
+		<compiler.plugin.version>3.8.1</compiler.plugin.version>
 		<datagen.version>2.2.1</datagen.version>
 
 		<!-- Disable XML reports by default. Enabled manually by passing -DdisableXmlReport=false in CI environment -->