chore: update linter versions & lint code (#84)

.eslintrc.js

@@ -7,7 +7,7 @@ module.exports = {
     parser: '@typescript-eslint/parser', // Specifies the ESLint parser
     extends: [
         'airbnb-base',
-        'prettier/@typescript-eslint', // Uses eslint-config-prettier to disable ESLint rules from @typescript-eslint/eslint-plugin that would conflict with prettier
+        'prettier', // Uses eslint-config-prettier to disable ESLint rules from @typescript-eslint/eslint-plugin that would conflict with prettier
         'plugin:prettier/recommended', // Enables eslint-plugin-prettier and displays prettier errors as ESLint errors. Make sure this is always the last configuration in the extends array.
     ],
     plugins: ['@typescript-eslint'],

package.json

@@ -34,17 +34,17 @@
   "devDependencies": {
     "@types/jest": "^26.0.19",
     "@types/node": "^12",
-    "@typescript-eslint/eslint-plugin": "^4.11.1",
-    "@typescript-eslint/parser": "^4.11.1",
-    "eslint": "^6.8.0",
-    "eslint-config-airbnb-base": "^14.0.0",
-    "eslint-config-prettier": "^6.10.0",
-    "eslint-plugin-import": "^2.20.0",
-    "eslint-plugin-prettier": "^3.1.2",
+    "@typescript-eslint/eslint-plugin": "^4.33.0",
+    "@typescript-eslint/parser": "^4.33.0",
+    "eslint": "^7.32.0",
+    "eslint-config-airbnb-base": "^14.2.1",
+    "eslint-config-prettier": "^8.3.0",
+    "eslint-plugin-import": "^2.24.2",
+    "eslint-plugin-prettier": "^4.0.0",
     "jest": "^26.6.3",
     "jest-each": "^26.4.2",
     "jest-mock-extended": "^1.0.8",
-    "prettier": "^1.19.1",
+    "prettier": "^2.4.1",
     "ts-jest": "^26.4.4",
     "typescript": "^4.1.3"
   },