Remove version of override for resources plugin

Closes gh-9537

Author: snicoll

spring-boot-starters/spring-boot-starter-parent/pom.xml

@@ -122,7 +122,6 @@
 				<plugin>
 					<groupId>org.apache.maven.plugins</groupId>
 					<artifactId>maven-resources-plugin</artifactId>
-					<version>2.6</version>
 					<configuration>
 						<delimiters>
 							<delimiter>${resource.delimiter}</delimiter>