bump aws sdk version to support EKS IAM roles for service accounts

[vavvolo]

see aws/aws-sdk-java#2136

[gkatzioura]

Most probably will release on the weekend.

[dbirks]

Was having a problem with assuming roles, and found that building the wagon off of master with the updated sdk fixed my issue. Looking forward to a release whenever you get time 👍

Thank you for making this wagon open source and spending your time on it!

[dbirks]

I think the Travis build only failed because it was missing a signing key:

[secure]: keyring `/home/travis/.gnupg/secring.[secure]' created
[secure]: keyring `/home/travis/.gnupg/pubring.[secure]' created
[secure]: no default secret key: secret key not available
[secure]: signing failed: secret key not available

@gkatzioura - sorry to @ mention you directly. If you're able to fix the key signing issue sometime, I would greatly appreciate it 👍