Revert inadvertently-changed maven compiler plugin version (#597)

Author: sliver007

pom.xml

@@ -309,7 +309,7 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-compiler-plugin</artifactId>
-                    <version>3.12.0-SNAPSHOT</version>
+                    <version>3.11.0</version>
                     <configuration>
                         <failOnWarning>true</failOnWarning>
                         <showWarnings>true</showWarnings>