Bump league/commonmark from 1.5.5 to 1.5.6

Bumps [league/commonmark](https://github.com/thephpleague/commonmark) from 1.5.5 to 1.5.6.
- [Release notes](https://github.com/thephpleague/commonmark/releases)
- [Changelog](https://github.com/thephpleague/commonmark/blob/1.5.6/CHANGELOG.md)
- [Commits](https://github.com/thephpleague/commonmark/compare/1.5.5...1.5.6)

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

composer.lock

@@ -320,7 +320,7 @@
             "keywords": [
                 "laravel"
             ],
-            "abandoned": true,
+            "abandoned": "diglactic/laravel-breadcrumbs",
             "time": "2019-12-30T22:50:51+00:00"
         },
         {
@@ -2010,16 +2010,16 @@
         },
         {
             "name": "league/commonmark",
-            "version": "1.5.5",
+            "version": "1.5.6",
             "source": {
                 "type": "git",
                 "url": "https://github.com/thephpleague/commonmark.git",
-                "reference": "45832dfed6007b984c0d40addfac48d403dc6432"
+                "reference": "a56e91e0fa1f6d0049153a9c34f63488f6b7ce61"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/thephpleague/commonmark/zipball/45832dfed6007b984c0d40addfac48d403dc6432",
+                "url": "https://api.github.com/repos/thephpleague/commonmark/zipball/a56e91e0fa1f6d0049153a9c34f63488f6b7ce61",
-                "reference": "45832dfed6007b984c0d40addfac48d403dc6432",
+                "reference": "a56e91e0fa1f6d0049153a9c34f63488f6b7ce61",
                 "shasum": ""
             },
             "require": {
@@ -2101,7 +2101,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2020-09-13T14:44:46+00:00"
+            "time": "2020-10-17T21:33:03+00:00"
         },
         {
             "name": "league/csv",