Update to dynapath 0.2.5

[tobias]

Before submitting a PR make sure the following things have been done:

• The commits are consistent with our contribution guidelines
• You've added tests to cover your change(s)
• All tests are passing
• The new code is not generating reflection warnings
• You've updated the readme (if adding/changing middleware)

Thanks!

This version addresses two Java 9 related issues:

• 0.2.4 would fail under Java 9 if AOT'd
• the latest Java 9 build (9-ea+148) broke dynapath's reflection to make
  URLClassLoader modifiable

[bbatsov]

Thanks! 👍