Bump phpmailer/phpmailer from 5.2.24 to 6.5.0 in /tpl

Bumps [phpmailer/phpmailer](https://github.com/PHPMailer/PHPMailer) from 5.2.24 to 6.5.0.
- [Release notes](https://github.com/PHPMailer/PHPMailer/releases)
- [Changelog](https://github.com/PHPMailer/PHPMailer/blob/master/changelog.md)
- [Commits](PHPMailer/PHPMailer@v5.2.24...v6.5.0)

---
updated-dependencies:
- dependency-name: phpmailer/phpmailer
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

tpl/composer.json

@@ -1,6 +1,6 @@
 {
     "require": {
         "rain/raintpl": ">=3.0.0",
-        "phpmailer/phpmailer": "~5.2"
+        "phpmailer/phpmailer": "~6.5"
     }
 }