Update version to 4.0

Author: jleyva

version.php

@@ -24,8 +24,8 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$plugin->version = 2019061900;
+$plugin->version = 2021060200;
 $plugin->requires = 2016120500; // Moodle 3.2.
 $plugin->component = 'availability_mobileapp';
 $plugin->maturity = MATURITY_STABLE;
-$plugin->release  = '3.0';
+$plugin->release  = '4.0';