chore: deprecate action in favor of GitHub App token action (#360)

* chore: deprecate action in favor of GitHub App token action

* chore: deprecate action in favor of GitHub App token action

* Update README.md

Co-authored-by: Ron <45816308+rjaegers@users.noreply.github.com>

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Co-authored-by: Ron <45816308+rjaegers@users.noreply.github.com>

README.md

@@ -1,5 +1,11 @@
 # App token action
 
+> [!IMPORTANT]
+> This action is deprecated. Please migrate to the [github-app-token-action](https://github.com/actions/create-github-app-token). 
+>
+> Migration is almost straight forward, be-aware that GitHub actions requires the key as input and not the base64 encoded version of the private key. See [here](https://github.com/actions/create-github-app-token?tab=readme-ov-file#private-key) how to do that securely.
+
+
 A GitHub action that obtains a token for an app authorization which can used instead of a personal access token (PAT) for example. Currently the *app* and *installation* scope are supported. For more details check out the GitHub App authentication [docs](https://docs.github.com/en/free-pro-team@latest/developers/apps/authenticating-with-github-apps)
 
 Before the action can be used the APP has to be installed on the subject repository or in the organization scope.