Update Security starter to depend on single copy of AOP Alliance classes

As of Spring Framework 4.3, spring-aop now embeds the classes from the
aopalliance:aopalliance jar. This means that the transitive dependency
on aopalliance:aopalliance is redundant and it can be excluded.

Closes gh-6159

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

@@ -29,10 +29,22 @@
 		<dependency>
 			<groupId>org.springframework.security</groupId>
 			<artifactId>spring-security-config</artifactId>
+			<exclusions>
+				<exclusion>
+					<groupId>aopalliance</groupId>
+					<artifactId>aopalliance</artifactId>
+				</exclusion>
+			</exclusions>
 		</dependency>
 		<dependency>
 			<groupId>org.springframework.security</groupId>
 			<artifactId>spring-security-web</artifactId>
+			<exclusions>
+				<exclusion>
+					<groupId>aopalliance</groupId>
+					<artifactId>aopalliance</artifactId>
+				</exclusion>
+			</exclusions>
 		</dependency>
 	</dependencies>
 </project>