Update request dependency

[onury]

NPM warnings when iyzipay is installed for a project:

npm WARN deprecated tough-cookie@2.2.2: ReDoS vulnerability parsing Set-Cookie https://nodesecurity.io/advisories/130
npm WARN deprecated node-uuid@1.4.8: Use uuid module instead
npm WARN deprecated boom@2.10.1: This version is no longer maintained. Please upgrade to the latest version.
npm WARN deprecated cryptiles@2.0.5: This version is no longer maintained. Please upgrade to the latest version.
npm WARN deprecated hoek@2.16.3: This version is no longer maintained. Please upgrade to the latest version.

Most of these issues below are addressed in latest version of request (as of July 2019).

[nb256]

2 high severity vulnerabilities exist on current dependencies and they can be seen on npm audit logs:

Regular Expression Denial of Service
tough-cookie
https://www.npmjs.com/advisories/525

Insufficient Entropy
cryptiles
https://www.npmjs.com/advisories/1464

[mertssmnoglu]

Request package is deprecated and have many vulnerabilities. iyzipay-node package is a payment library that should focus on the security. You should migrate to another web-http library/framework.