Add an option to choose the base tag for the diff

[Conaclos]

Hi!

I am working on a project where every time we release, we create two release: one for cli release and the other for the lsp release. For example the 1.1.0 version is released as cli/v1.1.0 and lsp/v1.2.0 (the versions are different because of vscode naming convention).

The issue we encounter, is that one release got tagged first and the second got wrong generated release notes because the diff is made between the new release and the last commit (resulting in an empty diff).
For example, if cli/v1.1.0 is released first, the release notes of lsp/v1.2.0 is generated using a diff between cli/v1.1.0 and main.

This GitHub action could provide an option to select the base tag for the diff.