Bump league/commonmark from 1.6.2 to 1.6.4

Bumps [league/commonmark](https://github.com/thephpleague/commonmark) from 1.6.2 to 1.6.4.
- [Release notes](https://github.com/thephpleague/commonmark/releases)
- [Changelog](https://github.com/thephpleague/commonmark/blob/main/CHANGELOG-1.x.md)
- [Commits](https://github.com/thephpleague/commonmark/compare/1.6.2...1.6.4)

---
updated-dependencies:
- dependency-name: league/commonmark
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

composer.lock

@@ -2327,16 +2327,16 @@
         },
         {
             "name": "league/commonmark",
-            "version": "1.6.2",
+            "version": "1.6.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/thephpleague/commonmark.git",
-                "reference": "7d70d2f19c84bcc16275ea47edabee24747352eb"
+                "reference": "c3c8b7217c52572fb42aaf84211abccf75a151b2"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/thephpleague/commonmark/zipball/7d70d2f19c84bcc16275ea47edabee24747352eb",
-                "reference": "7d70d2f19c84bcc16275ea47edabee24747352eb",
+                "url": "https://api.github.com/repos/thephpleague/commonmark/zipball/c3c8b7217c52572fb42aaf84211abccf75a151b2",
+                "reference": "c3c8b7217c52572fb42aaf84211abccf75a151b2",
                 "shasum": ""
             },
             "require": {
@@ -2354,7 +2354,7 @@
                 "github/gfm": "0.29.0",
                 "michelf/php-markdown": "~1.4",
                 "mikehaertl/php-shellcommand": "^1.4",
-                "phpstan/phpstan": "^0.12",
+                "phpstan/phpstan": "^0.12.90",
                 "phpunit/phpunit": "^7.5 || ^8.5 || ^9.2",
                 "scrutinizer/ocular": "^1.5",
                 "symfony/finder": "^4.2"
@@ -2424,7 +2424,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-05-12T11:39:41+00:00"
+            "time": "2021-06-19T20:08:14+00:00"
         },
         {
             "name": "league/csv",