TypeError: Issuer (iss) must be a string when using GitHub App authentication

[timdittler]

Description

When using GitHub App authentication, the action fails with a TypeError because the app_id is passed as an integer to PyJWT, which now requires the iss claim to be a string.

Error

Traceback (most recent call last):
  File "/action/workspace/cleanowners.py", line 340, in <module>
    main()
  File "/action/workspace/cleanowners.py", line 42, in main
    github_connection = auth.auth_to_github(
  File "/action/workspace/auth.py", line 33, in auth_to_github
    gh.login_as_app_installation(
  File "/usr/local/lib/python3.14/site-packages/github3/github.py", line 1516, in login_as_app_installation
    jwt_token = apps.create_token(
  File "/usr/local/lib/python3.14/site-packages/github3/apps.py", line 175, in create_token
    token = jwt.encode(
        payload={"iat": now, "exp": now + expire_in, "iss": app_id},
        ...
    )
  File "/usr/local/lib/python3.14/site-packages/jwt/api_jwt.py", line 145, in encode
    raise TypeError("Issuer (iss) must be a string.")
TypeError: Issuer (iss) must be a string.

Root Cause

This is a known issue in github3.py v4.0.1, which is pinned in this action's requirements.txt. The fix has been merged upstream:

• Issue: Invalid issuer (int instead of str) when creating a GitHub App token sigmavirus24/github3.py#1306
• Fix: Cast GitHub app_id as string before using as iss sigmavirus24/github3.py#1307 (merged 2026-02-03)

However, no new release of github3.py has been published since v4.0.1 (April 2023).

Suggested Fix

Either:

1. Pin github3.py to the commit with the fix (b7cf6114c76f9a731e44572a24d531645c3a3e85)
2. Wait for a new github3.py release and update requirements.txt

Environment

• Action version: v1.2.13 / v1.3.0
• Docker image: ghcr.io/github/cleanowners:v1
• Python version in image: 3.14