feat!: remove deprecated inputs (#213)

BREAKING CHANGE: Removed deprecated inputs (`app_id`, `private_key`, `skip_token_revoke`) and made `app-id` and `private-key` required in the action configuration.

tests/snapshots/index.js.md

@@ -12,9 +12,7 @@ Generated by [AVA](https://avajs.dev).
 
 > stdout
 
-    `app_id — 'app_id' is deprecated and will be removed in a future version. Use 'app-id' instead.␊
-    private_key — 'private_key' is deprecated and will be removed in a future version. Use 'private-key' instead.␊
-    skip_token_revoke — 'skip_token_revoke' is deprecated and will be removed in a future version. Use 'skip-token-revoke' instead.`
+    ''
 
 ## main-custom-github-api-url.test.js
 
@@ -39,16 +37,6 @@ Generated by [AVA](https://avajs.dev).
     POST /api/v3/app/installations/123456/access_tokens␊
     {"repositories":["create-github-app-token"]}`
 
-## main-missing-app-id.test.js
-
-> stderr
-
-    'Input required and not supplied: app-id'
-
-> stdout
-
-    ''
-
 ## main-missing-owner.test.js
 
 > stderr
@@ -59,16 +47,6 @@ Generated by [AVA](https://avajs.dev).
 
     ''
 
-## main-missing-private-key.test.js
-
-> stderr
-
-    'Input required and not supplied: private-key'
-
-> stdout
-
-    ''
-
 ## main-missing-repository.test.js
 
 > stderr