Compare meta value and Mollie ID as binary strings to avoid collate i…

…ssues.

See #32 (comment).

Co-Authored-By: Reüel van der Steege <10371164+rvdsteege@users.noreply.github.com>

src/Install.php

@@ -354,7 +354,7 @@ private function convert_user_meta() {
 				$wpdb->pronamic_pay_mollie_customers AS mollie_customer
 					INNER JOIN
 				$wpdb->usermeta AS wp_user_meta
-						ON wp_user_meta.meta_value = mollie_customer.mollie_id
+						ON BINARY wp_user_meta.meta_value = mollie_customer.mollie_id
 					INNER JOIN
 				$wpdb->users AS wp_user
 						ON wp_user_meta.user_id = wp_user.ID