[CORE-69] Update netty

[calypsomatic]

Addresses https://github.com/broadinstitute/firecloud-orchestration/security/dependabot/83 by upgrading the netty version to 4.1.115.

Have you read CONTRIBUTING.md lately? If not, do that first.

I, the developer opening this PR, do solemnly pinky swear that:

• I've followed the instructions if I've made any changes to the API, especially if they're breaking changes
• I've updated the FISMA documentation if I've made any security-related changes, including auth, encryption, or auditing

In all cases:

• Get two thumbsworth of review and PO signoff if necessary
• Verify all tests go green
• Squash and merge. Make sure your branch deletes; GitHub should do this for you.
• Test this change deployed correctly and works on dev environment after deployment