New changelog scripts (#4491)

* Add templates

* Add folder for local storage of the digests

* Add first draft of the changelog scripts

* Enable Audits in the change template

* Fixes for Polkadot

* Fix templating issue in case there is no high prio change

* Fix Ruby setup

* Remove shell

* Fix chain names

* Fix ENV

* Fix how to get runtime

* Fix runtime_dir

* Fix context location

* Pin changelogerator to a specific version

polkadot/scripts/github/lib.rb

@@ -1,12 +1,10 @@
 # frozen_string_literal: true
 
-# A collection of helper functions that might be useful for various scripts
-
-# Gets the runtime version for a given runtime.
+# Gets the runtime version for a given runtime from the filesystem.
 # Optionally accepts a path that is the root of the project which defaults to
 # the current working directory
-def get_runtime(runtime, path = '.')
-  File.open(path + "/runtime/#{runtime}/src/lib.rs") do |f|
+def get_runtime(runtime: nil, path: '.', runtime_dir: 'runtime')
+  File.open(path + "/#{runtime_dir}/#{runtime}/src/lib.rs") do |f|
     f.find { |l| l =~ /spec_version/ }.match(/[0-9]+/)[0]
   end
 end