Disable autocomplete for SMTP Password

While really nearly no modern browser cares about it anymore too much it's still not wrong to have it here (and also stops some automated scanners reporting this...)

settings/templates/admin.php

@@ -450,7 +450,7 @@ if ($_['suggestedOverwriteCliUrl']) {
 			<label for="mail_smtpname"><?php p($l->t( 'Credentials' )); ?></label>
 			<input type="text" name='mail_smtpname' id="mail_smtpname" placeholder="<?php p($l->t('SMTP Username'))?>"
 				   value='<?php p($_['mail_smtpname']) ?>' />
-			<input type="password" name='mail_smtppassword' id="mail_smtppassword"
+			<input type="password" name='mail_smtppassword' id="mail_smtppassword" autocomplete="off"
 				   placeholder="<?php p($l->t('SMTP Password'))?>" value='<?php p($_['mail_smtppassword']) ?>' />
 			<input id="mail_credentials_settings_submit" type="button" value="<?php p($l->t('Store credentials')) ?>">
 		</p>