Upgrade Wireshark to v1.12.2

Just noticed that wireshark wasn't downloading on cask 'cause they bumped the version number. Not sure if someone has submitted already but didn't see it with a quick search so... here's a pull request... The sha256 was calculated locally after downloading on my computer -- not sure if that fits security protocol or not.

Release notes: https://www.wireshark.org/docs/relnotes/wireshark-1.12.2.html