feat: Remove support for Node 12 (#79)

BREAKING CHANGE: Remove support for Node 12.

Author: mtrezza

.github/workflows/ci.yml

@@ -53,8 +53,6 @@ jobs:
     strategy:
       matrix:
         include:
-          - name: Node 12
-            NODE_VERSION: 12
           - name: Node 14
             NODE_VERSION: 14
           - name: Node 16

README.md

@@ -5,7 +5,7 @@
 [![Coverage](https://codecov.io/gh/parse-community/parse-server-api-mail-adapter/branch/alpha/graph/badge.svg)](https://codecov.io/gh/parse-community/parse-server-api-mail-adapter)
 [![auto-release](https://img.shields.io/badge/%F0%9F%9A%80-auto--release-9e34eb.svg)](https://github.com/parse-community/parse-dashboard/releases)
 
-[![Node Version](https://img.shields.io/badge/nodejs-12,_14,_16,_18-green.svg?logo=node.js&style=flat)](https://nodejs.org)
+[![Node Version](https://img.shields.io/badge/nodejs-14,_16,_18-green.svg?logo=node.js&style=flat)](https://nodejs.org)
 
 [![dependency up-to-date](https://img.shields.io/librariesio/release/npm/parse-server-api-mail-adapter)](https://libraries.io/npm/parse-server-api-mail-adapter)
 [![weekly downloads](https://img.shields.io/npm/dw/parse-server-api-mail-adapter)](https://www.npmjs.com/package/parse-server-api-mail-adapter)