Fix types not assignable to 'ColorActionName'.

[lucyyyyyyy]

Fix 'lighten' and 'darken' not assignable to type 'ColorActionName'.

What's Changing and Why

Adding 'lighten' and 'darken' to ColorActionName to prevent the following errors

Type '"darken"' is not assignable to type 'ColorActionName'.```

## What else might be affected
Nothing

## Tasks

- [ ] Add tests
- [ ] Update Documentation
- [ ] Update `jimp.d.ts`
- [ ] Add [SemVer](https://semver.org/) Label

<!-- GITHUB_RELEASE PR BODY: canary-version -->
<details>
  <summary>📦 Published PR as canary version: <code>0.16.2-canary.1086.1311.0</code></summary>
  <br />
  
  :sparkles: Test out this PR locally via:
  
  ```sh
  npm install @jimp/cli@0.16.2-canary.1086.1311.0
  npm install @jimp/core@0.16.2-canary.1086.1311.0
  npm install @jimp/custom@0.16.2-canary.1086.1311.0
  npm install jimp@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-blit@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-blur@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-circle@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-color@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-contain@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-cover@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-crop@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-displace@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-dither@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-fisheye@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-flip@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-gaussian@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-invert@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-mask@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-normalize@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-print@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-resize@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-rotate@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-scale@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-shadow@0.16.2-canary.1086.1311.0
  npm install @jimp/plugin-threshold@0.16.2-canary.1086.1311.0
  npm install @jimp/plugins@0.16.2-canary.1086.1311.0
  npm install @jimp/test-utils@0.16.2-canary.1086.1311.0
  npm install @jimp/bmp@0.16.2-canary.1086.1311.0
  npm install @jimp/gif@0.16.2-canary.1086.1311.0
  npm install @jimp/jpeg@0.16.2-canary.1086.1311.0
  npm install @jimp/png@0.16.2-canary.1086.1311.0
  npm install @jimp/tiff@0.16.2-canary.1086.1311.0
  npm install @jimp/types@0.16.2-canary.1086.1311.0
  npm install @jimp/utils@0.16.2-canary.1086.1311.0
  # or 
  yarn add @jimp/cli@0.16.2-canary.1086.1311.0
  yarn add @jimp/core@0.16.2-canary.1086.1311.0
  yarn add @jimp/custom@0.16.2-canary.1086.1311.0
  yarn add jimp@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-blit@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-blur@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-circle@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-color@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-contain@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-cover@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-crop@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-displace@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-dither@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-fisheye@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-flip@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-gaussian@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-invert@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-mask@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-normalize@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-print@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-resize@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-rotate@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-scale@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-shadow@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugin-threshold@0.16.2-canary.1086.1311.0
  yarn add @jimp/plugins@0.16.2-canary.1086.1311.0
  yarn add @jimp/test-utils@0.16.2-canary.1086.1311.0
  yarn add @jimp/bmp@0.16.2-canary.1086.1311.0
  yarn add @jimp/gif@0.16.2-canary.1086.1311.0
  yarn add @jimp/jpeg@0.16.2-canary.1086.1311.0
  yarn add @jimp/png@0.16.2-canary.1086.1311.0
  yarn add @jimp/tiff@0.16.2-canary.1086.1311.0
  yarn add @jimp/types@0.16.2-canary.1086.1311.0
  yarn add @jimp/utils@0.16.2-canary.1086.1311.0

[hipstersmoothie]

🚀 PR was released in v0.17.7 🚀