Update tslint in / from 5.8.0 to 5.12.1

[dependencies]

Dependencies.io has updated tslint (a npm dependency in /) from "5.8.0" to "5.12.1".

5.12.1

🛠️ Bugfixes & enhancements

• [bugfix] Revert breaking change to tslint:recommended, update tslint:latest (#4404)
• [bugfix] Correcting fixer for the increment-decrement rule (#4415)
• [bugfix] Fix strict-type-predicates with unknown (#4444)
• [bugfix] Skip linting of .json files to avoid problems with --resolveJsonModule compiler option (#4001)
• [bugfix] fix some quotemark issues when using backticks with the avoid-template option (#4408)
• [enhancement] Mention file names in test script parse failures (#4397)

Thanks to our contributors!

• Young Min Kim
• Enes SOYLU
• Thomas den Hollander
• Adrian Leonhard