lint: add lint:dependencies using depcheck (#57)

* lint: add lint:dependencies using depcheck

* chore: add packages from ./.yarn/plugins/@yarnpkg/plugin-constraints.cjs to depcheckIgnore

Author: legobeat

.depcheckrc.json

@@ -0,0 +1,15 @@
+{
+  "ignores": [
+    "@lavamoat/allow-scripts",
+    "@lavamoat/preinstall-always-fail",
+    "@metamask/auto-changelog",
+    "@types/*",
+    "@yarnpkg/cli",
+    "@yarnpkg/core",
+    "@yarnpkg/fslib",
+    "clipanion",
+    "prettier-plugin-packagejson",
+    "ts-node",
+    "typedoc"
+  ]
+}

package.json

@@ -14,7 +14,8 @@
   "scripts": {
     "build": "tsc --project tsconfig.build.json",
     "build:clean": "rimraf dist && yarn build",
-    "lint": "yarn lint:eslint && yarn lint:misc --check",
+    "lint": "yarn lint:eslint && yarn lint:misc --check && yarn lint:dependencies",
+    "lint:dependencies": "depcheck",
     "lint:eslint": "eslint . --cache --ext js,ts",
     "lint:fix": "yarn lint:eslint --fix && yarn lint:misc --write",
     "lint:misc": "prettier '**/*.json' '**/*.md' '!CHANGELOG.md' '**/*.yml' '!.yarnrc.yml' --ignore-path .gitignore --no-error-on-unmatched-pattern",
@@ -42,6 +43,7 @@
     "@types/readable-stream": "^2.3.9",
     "@typescript-eslint/eslint-plugin": "^4.21.0",
     "@typescript-eslint/parser": "^4.21.0",
+    "depcheck": "^1.4.5",
     "eslint": "^7.23.0",
     "eslint-config-prettier": "^8.1.0",
     "eslint-plugin-import": "^2.22.1",