Set release instead of source/target for compiler plugin

Should fix :
```
17:06:19  [WARNING] bootstrap class path not set in conjunction with
-source 8
17:06:19  [WARNING] source value 8 is obsolete and will be removed in a
future release
17:06:19  [WARNING] target value 8 is obsolete and will be removed in a
future release
17:06:19  [WARNING] To suppress warnings about obsolete options, use
-Xlint:-options.
```
in the build.

Author: akurtakov

org.eclipse.m2e.maven.runtime/pom.xml

@@ -228,8 +228,7 @@
 					<artifactId>maven-compiler-plugin</artifactId>
 					<version>3.13.0</version>
 					<configuration>
-						<source>1.8</source>
-						<target>1.8</target>
+						<release>8</release>
 						<proc>none</proc>
 					</configuration>
 				</plugin>