Upgrade to maven-compiler-plugin 3.8.1

Closes gh-236

Author: philwebb

pom.xml

@@ -100,7 +100,7 @@
 				<plugin>
 					<groupId>org.apache.maven.plugins</groupId>
 					<artifactId>maven-compiler-plugin</artifactId>
-					<version>3.8.0</version>
+					<version>3.8.1</version>
 				</plugin>
 				<plugin>
 					<groupId>org.apache.maven.plugins</groupId>