Added detection for avif files

Also dropped official support for PHP < 7.2 (it works under 7.1 and 7.0, but that's not guaranteed for the future)

Author: SoftCreatR

.gitignore

@@ -2,3 +2,4 @@ composer.phar
 /vendor/
 .idea
 phpunit.xml
+.phpunit.result.cache

.travis.yml

@@ -1,9 +1,9 @@
 language: php
 
 php:
-  - 7.1
   - 7.2
   - 7.3
+  - 7.4
   - nightly
 
 matrix:

composer.json

@@ -23,12 +23,12 @@
         "issues": "https://github.com/SoftCreatR/php-mime-detector/issues",
         "forum": "https://support.softcreatr.com"
     },
-    "version": "3.0.0",
+    "version": "3.1.0",
     "require": {
-        "php": ">=7.1.0"
+        "php": ">=7.2.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "~7.0"
+        "phpunit/phpunit": "^8"
     },
     "autoload": {
         "psr-4": {