feat(action): allow configuring the github token and set it when it exists (#34)

* fix: set Bearer token in curl request when GITHUB_TOKEN is set

Signed-off-by: Ludovic Ortega <ludovic.ortega@adminafk.fr>

* fix: use a dedicated input variable to pass github token

Signed-off-by: Ludovic Ortega <ludovic.ortega@adminafk.fr>

* fix: use github_token inputs

Signed-off-by: Ludovic Ortega <ludovic.ortega@adminafk.fr>

* Update README.md

* Update README.md

---------

Signed-off-by: Ludovic Ortega <ludovic.ortega@adminafk.fr>
Co-authored-by: Orhun Parmaksız <orhunparmaksiz@gmail.com>

README.md

@@ -9,6 +9,7 @@ This action generates a changelog based on your Git history using [git-cliff](ht
 - `version`: `git-cliff` version to use. (e.g. `"latest"`, `"v2.5.0"`)
 - `config`: Path of the configuration file. (Default: `"cliff.toml"`)
 - `args`: [Arguments](https://github.com/orhun/git-cliff#usage) to pass to git-cliff. (Default: `"-v"`)
+- `github_token`: The GitHub API token used to get `git-cliff` release information via the GitHub API to avoid rate limits. (Default: `${{ github.token }}`)
 
 ### Output variables
 
@@ -32,6 +33,13 @@ This action generates a changelog based on your Git history using [git-cliff](ht
 >
 > Otherwise, you might end up getting empty changelogs or `git ref` errors depending on arguments passed to `git-cliff`.
 
+### Running the action outside of GitHub
+
+If you run the action in Gitea or GitHub Enterprise, the `github_token` input is invalid. You have two options:
+
+- Pass an empty value (`github_token: ""`) (limit of 60 requests per hour per IP address).
+- Create a GitHub token and pass it through GitHub secrets to avoid rate limiting.
+
 ### Examples
 
 #### Simple