Regex of the validateVersion method of class Plugin modified to match…

… every possible version string of the current list of versions of Advanced Custom Fields

src/ACFProInstaller/Plugin.php

@@ -184,7 +184,7 @@ protected function validateVersion($version)
     {
         // \A = start of string, \Z = end of string
         // See: http://stackoverflow.com/a/34994075
-        $major_minor_patch_optional = '/\A\d\.\d\.\d{1,2}(?:\.\d)?\Z/';
+        $major_minor_patch_optional = '/\A\d\.\d\.\d{1,2}(?:\.\d)?(?:\-(dev|beta|RC)?(\d{1,2})?)?\Z/';
 
         if (!preg_match($major_minor_patch_optional, $version)) {
             throw new \UnexpectedValueException(