Use a random port for Spring Boot testcases (#1877)

diff --git a/elasticjob-lite/elasticjob-lite-spring/elasticjob-lite-spring-boot-starter/src/test/resources/application-snapshot.yml b/elasticjob-lite/elasticjob-lite-spring/elasticjob-lite-spring-boot-starter/src/test/resources/application-snapshot.yml
index 022757b..64469a2 100644
--- a/elasticjob-lite/elasticjob-lite-spring/elasticjob-lite-spring-boot-starter/src/test/resources/application-snapshot.yml
+++ b/elasticjob-lite/elasticjob-lite-spring/elasticjob-lite-spring-boot-starter/src/test/resources/application-snapshot.yml
@@ -17,7 +17,7 @@
 
 elasticjob:
   dump:
-    port: 8888
+    port: 0
   regCenter:
     serverLists: localhost:18181
     namespace: elasticjob-lite-spring-boot-starter