Remove unwanted override of resource plugin's version

Closes gh-13607

Author: wilkinsona

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

@@ -123,7 +123,6 @@
 				<plugin>
 					<groupId>org.apache.maven.plugins</groupId>
 					<artifactId>maven-resources-plugin</artifactId>
-					<version>2.6</version>
 					<configuration>
 						<delimiters>
 							<delimiter>${resource.delimiter}</delimiter>