Updated to support PHP 7.1+ or PHP 8.0

On branch updated-for-php8
Changes to be committed:
	modified:   .gitignore
	modified:   composer.json

Author: CobraSphere-IB

.gitignore

@@ -4,4 +4,5 @@ nbproject/*
 .idea
 composer.lock
 build
-_notes
+_notes
+.phpunit.result.cache

composer.json

@@ -6,7 +6,7 @@
     "keywords": ["mailerlite", "sdk", "email", "marketing"],
     "type": "library",
     "require": {
-        "php" : "^8.0",
+        "php" : "7.1 || ^8.0",
         "php-http/client-common": "^2.0",
         "php-http/discovery": "^1.7",
         "nyholm/psr7": "^1.0",