fix: Update isort config to include markdown module and fix import ordering

Co-authored-by: zkoppert <[email protected]>

Author: Copilot

.github/linters/.isort.cfg

@@ -1,4 +1,4 @@
 [settings]
 profile = black
 known_third_party = github3,dateutil,dotenv
-known_first_party = auth
+known_first_party = auth,markdown

stale_repos.py

@@ -9,9 +9,9 @@
 import github3
 from dateutil.parser import parse
 from env import get_env_vars
-from markdown import write_to_markdown
 
 import auth
+from markdown import write_to_markdown
 
 
 def main():  # pragma: no cover