Add type for parseAccountFlags (#1258)

* Return type is `Settings`
* Bump @typescript-eslint/parser to 2.27.0
* Bump yarn.lock
* Release 1.6.6-beta.1

package.json

@@ -1,6 +1,6 @@
 {
   "name": "ripple-lib",
-  "version": "1.6.5",
+  "version": "1.6.6-beta.1",
   "license": "ISC",
   "description": "A TypeScript/JavaScript API for interacting with the XRP Ledger in Node.js and the browser",
   "files": [
@@ -37,7 +37,7 @@
     "@types/mocha": "^7.0.1",
     "@types/node": "^13.1.1",
     "@typescript-eslint/eslint-plugin": "^2.3.3",
-    "@typescript-eslint/parser": "^2.3.3",
+    "@typescript-eslint/parser": "^2.27.0",
     "assert-diff": "^3.0.0",
     "doctoc": "^1.4.0",
     "ejs": "^3.0.1",