Increase SampleIntegrationTests run timeouts

Increase the timeouts to give CI builds more time should dependencies
be missing.

spring-boot-cli/src/test/java/org/springframework/boot/cli/SampleIntegrationTests.java

@@ -63,7 +63,7 @@ public class SampleIntegrationTests {
 						return command;
 					}
 				});
-		this.command = future.get(4, TimeUnit.MINUTES);
+		this.command = future.get(6, TimeUnit.MINUTES);
 	}
 
 	@Before