Display README.md for packages (#303)

* Display README.md for packages

Extract the file from the latest release dist zip, and store rendered in the database.

* Introduce PackageDetails model

This holds the extra information required for the Package Details page (README)

* Test README sync

* Add missing zip file

* Remove test file after test run

* Show Readme for latest unstable release if non other exist

Fixes #306 by sorting the packages before picking the latest version.

* Refactor README extraction into it's own class

* PHPStan fix

* Remove todo

Functionality is already the same

* Update deps

* Revert "Update deps"

This reverts commit 8f3970f.

* Update the one package using Composer v1

composer.json

@@ -25,6 +25,7 @@
         "excelwebzone/recaptcha-bundle": "^1.5",
         "knplabs/github-api": "^2.12",
         "knpuniversity/oauth2-client-bundle": "^2.0",
+        "league/commonmark": "^1.5",
         "league/flysystem-bundle": "^1.5",
         "league/oauth2-github": "^2.0",
         "m4tthumphrey/php-gitlab-api": "^9.17",