parse-php-sdk refactor: upgrade @parse/simple-mailgun-adapter from 1.2.0 to 2.0.0

Snyk has created this PR to upgrade @parse/simple-mailgun-adapter from 1.2.0 to 2.0.0.

:information_source: Keep your dependencies up-to-date. This makes it easier to fix existing vulnerabilities and to more quickly identify and fix newly disclosed vulnerabilities when they affect your project.

Warning: This is a major version upgrade, and may be a breaking change.

The recommended version is 1 version ahead of your current version.
The recommended version was released 10 months ago, on 2021-04-07.

The recommended version fixes:

Severity	Issue	PriorityScore (*)	Exploit Maturity
	Remote Code Execution (RCE) SNYK-JS-PACRESOLVER-1564857	512/1000 Why? Proof of Concept exploit, CVSS 8.1	Proof of Concept
	Server-side Request Forgery (SSRF) SNYK-JS-NETMASK-1089716	512/1000 Why? Proof of Concept exploit, CVSS 8.1	Proof of Concept

(*) Note that the real score may have changed since the PR was raised.

Release notes

Package name: @parse/simple-mailgun-adapter

2.0.0 - 2021-04-07
DEPRECATED

This mail adapter has been deprecated. Instead, use one of the community provided mail adapters.

Breaking Changes
- Upgraded to new native mailgun.js driver that does not support the same options as the deprecated driver, see docs (Manuel Trezza) #37
1.2.0 - 2020-12-14
Merge pull request #36 from parse-community/release1.2.0

Bump version to 1.2.0