Add maven-compiler-plugin to plugin management

http-service/pom.xml

@@ -138,7 +138,6 @@
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-compiler-plugin</artifactId>
-				<version>3.5.1</version>
 				<configuration>
 					<annotationProcessorPaths>
 						<path>

pom.xml

@@ -223,6 +223,11 @@
 					<artifactId>maven-jar-plugin</artifactId>
 					<version>3.0.2</version>
 				</plugin>
+				<plugin>
+					<groupId>org.apache.maven.plugins</groupId>
+					<artifactId>maven-compiler-plugin</artifactId>
+					<version>3.6.1</version>
+				</plugin>
 			</plugins>
 		</pluginManagement>
 		<extensions>

runelite-mixins/pom.xml

@@ -60,7 +60,6 @@
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-compiler-plugin</artifactId>
-				<version>3.6.1</version>
 				<configuration>
 					<!-- RuneScape classes do not verify
 					 under Java 7+ due to the obfuscation