Check for required PHP version

file.php

public function admin_notice_minimum_php_version() {

	if ( isset( $_GET['activate'] ) ) unset( $_GET['activate'] );

	$message = sprintf(
		/* translators: 1: Plugin Name 2: PHP 3: Required PHP version */
		esc_html__( '"%1$s" requires "%2$s" version %3$s or greater.', 'text-domain' ),
		'<strong>' . esc_html__( 'Plugin Name', 'text-domain' ) . '</strong>',
		'<strong>' . esc_html__( 'PHP', 'text-domain' ) . '</strong>',
		 '5.4'
	);

	printf( '<div class="notice notice-warning is-dismissible"><p>%1$s</p></div>', $message );

}

if ( version_compare( PHP_VERSION, '5.4', '<' ) ) {
	add_action( 'admin_notices', 'admin_notice_minimum_php_version' );
}