Updated dep php_codesniffer, added support for php 7.0 - php 7.0 | php 8.0 (#63)

* set php version to >=7.0 or 8

Signed-off-by: fenn-cs <fenn25.fn@gmail.com>

* updated php_codesniffer

Signed-off-by: fenn-cs <fenn25.fn@gmail.com>

Author: nfebe

composer.json

@@ -29,15 +29,14 @@
         "source": "https://github.com/phpList/web-frontend"
     },
     "require": {
-        "php": "~7.0.0 || ~7.1.0 || ~7.2.0",
-
+        "php": "^7.0|^8.0",
         "phplist/core": "4.0.x-dev"
     },
     "require-dev": {
         "phpunit/phpunit": "^6.5.6",
         "phpunit/phpunit-mock-objects": "^5.0.6",
         "guzzlehttp/guzzle": "^6.3.0",
-        "squizlabs/php_codesniffer": "^3.2.0",
+        "squizlabs/php_codesniffer": "^3.5.8",
         "phpstan/phpstan": "^0.7.0",
         "nette/caching": "^2.5.0 || ^3.0.0",
         "nikic/php-parser": "^3.1.0",