feat: add GitHub Enterprise Server (GHES) support (#36)

This adds support for this action to be used in GitHub Enterprise
Server.

It sends request to the base url extracted from
[GITHUB_API_URL](https://docs.github.com/en/enterprise-server@3.10/actions/learn-github-actions/variables#default-environment-variables).

---------

Co-authored-by: Gregor Martynus <39992+gr2m@users.noreply.github.com>

main.js

@@ -15,9 +15,16 @@ const privateKey = core.getInput("private_key");
 
 const repository = process.env.GITHUB_REPOSITORY;
 
-main(appId, privateKey, repository, core, createAppAuth, request).catch(
+main(
-  (error) => {
+  appId,
-    console.error(error);
+  privateKey,
-    core.setFailed(error.message);
+  repository,
-  }
+  core,
-);
+  createAppAuth,
+  request.defaults({
+    baseUrl: process.env["GITHUB_API_URL"],
+  })
+).catch((error) => {
+  console.error(error);
+  core.setFailed(error.message);
+});

post.js

@@ -5,9 +5,12 @@ import { request } from "@octokit/request";
 
 import { post } from "./lib/post.js";
 
-post(core, request).catch(
+post(
-  (error) => {
+  core,
-    console.error(error);
+  request.defaults({
-    core.setFailed(error.message);
+    baseUrl: process.env["GITHUB_API_URL"],
-  }
+  })
-);
+).catch((error) => {
+  console.error(error);
+  core.setFailed(error.message);
+});