Add ESLint 7 to peerDependencies

Author: Keegan Lillo

package.json

@@ -45,7 +45,7 @@
   },
   "peerDependencies": {
     "@typescript-eslint/parser": "^1 || ^2",
-    "eslint": "^5 || ^6",
+    "eslint": "^5 || ^6 || ^7",
     "typescript": "^3"
   },
   "engines": {