feat: add check action

check.py

@@ -0,0 +1,37 @@
+#/usr/bin/env python3
+
+import os
+import re
+import sys
+import requests
+
+
+def get_github_version(repository: str) -> str:
+    res = requests.get(f"https://api.github.com/repos/{repository}/releases/latest").json()
+    return res["tag_name"].removeprefix("v")
+
+
+def does_pypi_version_exist(base_url: str, package: str, version: str) -> bool:
+    base_url = base_url.removesuffix("/")
+    version = version.replace(".", "\\.")
+
+    body = requests.get(f"{base_url}/simple/{package}").text
+    return len(re.findall(rf"<a href=\".+\">{package}-{version}-.+</a>", body, re.MULTILINE)) > 0
+
+
+def main():
+    repository = os.environ["REPOSITORY"]
+    package = os.environ["PACKAGE"]
+    base_url = os.environ["FORGEJO_URL"]
+
+    version = get_github_version(repository)
+
+    if does_pypi_version_exist(base_url, package, version):
+        sys.exit(0)
+
+    print(f"version=v{version}")
+
+
+if __name__ == "__main__":
+    main()
+