Add support for GitHub Enterprise (#152)

* use GITHUB_API_URL env var to support usage with GitHub Enterprise

* stringify github api error objects

* update lib

* test correct endpoint

* fix endpoint usage

* reset quotes

Author: simbo

lib/index.js

@@ -50,9 +50,9 @@ let configSource!: 'list' | 'repo'
     startGroup('Syncing labels...')
     const options: Options = {
       accessToken: getInput('token'),
+      endpoint: process.env.GITHUB_API_URL?.replace(/^https?:\/\//, ''),
       repo: process.env.GITHUB_REPOSITORY as string,
       labels,
-
       allowAddedLabels: getInput('delete-other-labels') != 'true',
       dryRun: getInput('dry-run') == 'true'
     }
@@ -85,7 +85,7 @@ let configSource!: 'list' | 'repo'
     core.info(msg.join('\n'))
     endGroup()
   } catch (e: any) {
-    log.fatal(e)
+    log.fatal(JSON.stringify(e))
   }
 })()
 
@@ -230,7 +230,7 @@ async function fetchRepoLabels(
 ): Promise<LabelInfo[]> {
   startGroup('Getting repo labels...')
 
-  const url = `https://api.github.com/repos/${repo}/labels`,
+  const url = `${process.env.GITHUB_API_URL}/repos/${repo}/labels`,
     headers = token ? { Authorization: `token ${token}` } : undefined
   log.info(`Using following URL: ${url}`)