Maximum call stack size exceeded on unavailable memcached
When memcached is unavailable, I get "Maximum call stack size exceeded" Error on line https://github.com/animir/node-rate-limiter-flexible/blob/master/lib/RateLimiterMemcache.js#L31
called from https://github.com/animir/node-rate-limiter-flexible/blob/master/lib/RateLimiterMemcache.js#L59 .

`attemptNumber` is never increased, which results in never ending loop. I believe `attemptNumber` should be increased on this line https://github.com/animir/node-rate-limiter-flexible/blob/master/lib/RateLimiterMemcache.js#L57

Reproduction code, memcached must be unavailable
```js
'use strict';

const {RateLimiterMemcache} = require('rate-limiter-flexible');
const Memcached = require('memcached');

const memcacheRateLimiterOpts = {
    points: 100, // 100 same events
    duration: 3600, // per 1 hour
    storeClient: new Memcached('127.0.0.1:12345', {timeout: 500, failures: 2, retries: 2})
};

const rateLimiter = new RateLimiterMemcache(memcacheRateLimiterOpts);

async function foobar() {
    await rateLimiter.consume('aaa');
}

foobar();
```