Minor update and added changelog

- Update to make composer.josn valid with no warnings

Signed-off-by: Scott-David Jones <scott.jones@autumndev.co.uk>

CHANGELOG.md

@@ -0,0 +1,18 @@
+# Changelog
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [3.1] - 2021-01-07
+### Changed
+- Updated License to GNU General Public License v3.0 or later
+- Updated Composer license identifier to correct GPL-3.0-or-later
+
+### Added
+- Changlog
+
+## [3.0] - 2021-01-07
+### Added
+- Official PHP 8 Support - Thanks to [racinmat](https://github.com/racinmat)
+- Carbon Immutable Support - Thansk to [racinmat](https://github.com/racinmat)

composer.json

@@ -7,15 +7,17 @@
         "jms/serializer": "^2.0 || ^3.0",
         "nesbot/carbon": "^2.5"
     },
-    "license": "GNU General Public License v2.0",
-    "authors": [{
-        "name": "autumndev",
-        "email": "sayhi@autumndev.co.uk"
-    }],
+    "license": "GPL-3.0-or-later",
+    "authors": [
+        {
+            "name": "autumndev",
+            "email": "sayhi@autumndev.co.uk"
+        }
+    ],
     "minimum-stability": "RC",
     "autoload": {
         "psr-0": {
             "AutumnDev": "src/"
         }
     }
-}
+}