v0.0.3

• Added a new working-directory parameter. When this is set, all actions are performed from inside this directory. Implemented by @Snoupix. GH #4.
• Fixed a bug where even when extra-files was set, the action would fail if there was no Changes.md file present. This contradicted the docs, which said that when extra-files was set, the changes-file parameter would be ignored. Reported by @jannes. GH #3.