[TechDebt] Big Updates

[ctsstc]

See if we can get these major updates handled, and old GreenKeeper PRs closed out.

Major Update Potentially breaking API changes. Use caution.

• ◯ @types/dotenv 6.1.1 ❯ 8.2.0
• ◯ discord.js 11.6.4 ❯ 12.2.0 https://github.com/discordjs/discord.js#readme
• ◯ tslint devDep 5.20.1 ❯ 6.1.1 https://palantir.github.io/tslint

Blockers

• [Refactor] Add new ExecutionContext class #109

Open GreenKeeper PRs

• Update discord.js to the latest version 🚀 #105
• Update @types/dotenv to the latest version 🚀 #96

[ctsstc]

Related, but no hope :RIP:
discordjs/discord.js#3978