Bump phpmailer/phpmailer from 6.2.0 to 6.4.1

Bumps [phpmailer/phpmailer](https://github.com/PHPMailer/PHPMailer) from 6.2.0 to 6.4.1.
- [Release notes](https://github.com/PHPMailer/PHPMailer/releases)
- [Changelog](https://github.com/PHPMailer/PHPMailer/blob/master/changelog.md)
- [Commits](https://github.com/PHPMailer/PHPMailer/compare/v6.2.0...v6.4.1)

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

composer.lock

@@ -150,16 +150,16 @@
         },
         {
             "name": "phpmailer/phpmailer",
-            "version": "v6.2.0",
+            "version": "v6.4.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/PHPMailer/PHPMailer.git",
-                "reference": "e38888a75c070304ca5514197d4847a59a5c853f"
+                "reference": "9256f12d8fb0cd0500f93b19e18c356906cbed3d"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/PHPMailer/PHPMailer/zipball/e38888a75c070304ca5514197d4847a59a5c853f",
-                "reference": "e38888a75c070304ca5514197d4847a59a5c853f",
+                "url": "https://api.github.com/repos/PHPMailer/PHPMailer/zipball/9256f12d8fb0cd0500f93b19e18c356906cbed3d",
+                "reference": "9256f12d8fb0cd0500f93b19e18c356906cbed3d",
                 "shasum": ""
             },
             "require": {
@@ -177,7 +177,7 @@
                 "yoast/phpunit-polyfills": "^0.2.0"
             },
             "suggest": {
-                "ext-mbstring": "Needed to send email in multibyte encoding charset",
+                "ext-mbstring": "Needed to send email in multibyte encoding charset or decode encoded addresses",
                 "hayageek/oauth2-yahoo": "Needed for Yahoo XOAUTH2 authentication",
                 "league/oauth2-google": "Needed for Google XOAUTH2 authentication",
                 "psr/log": "For optional PSR-3 debug logging",
@@ -214,7 +214,7 @@
             "description": "PHPMailer is a full-featured email creation and transfer class for PHP",
             "support": {
                 "issues": "https://github.com/PHPMailer/PHPMailer/issues",
-                "source": "https://github.com/PHPMailer/PHPMailer/tree/v6.2.0"
+                "source": "https://github.com/PHPMailer/PHPMailer/tree/v6.4.1"
             },
             "funding": [
                 {
@@ -222,7 +222,7 @@
                     "type": "github"
                 }
             ],
-            "time": "2020-11-25T15:24:57+00:00"
+            "time": "2021-04-29T12:25:04+00:00"
         },
         {
             "name": "psr/log",