Travis: update matrix of tested Spring versions

Author: jirutka

.travis.yml

@@ -7,10 +7,10 @@ env:
   global:
     secure: "DiliRHV1VROi28XVoFVupupLMVJ0IqyuJsBR2NyfjhAB4eOvwyRY78H2iNzZ5TPkgQ2x5roCE9vDF4WRlRGd/rTgs2YvRjCL2tOpjxYXgyjuFKq0HtnG6Jpr45LV7dmTxiAUXjiNUa9SSr30CXAOEM2dcPYjci3Ze7HV/5BtkSU="  # BINTRAY_API_KEY
   matrix:
-    - SPRING_VERSION=3.2.16.RELEASE
+    - SPRING_VERSION=3.2.17.RELEASE
     - SPRING_VERSION=4.0.9.RELEASE
     - SPRING_VERSION=4.1.9.RELEASE
-    - SPRING_VERSION=4.2.4.RELEASE
+    - SPRING_VERSION=4.2.6.RELEASE
 
 # Cache local Maven repository.
 cache: