Init flask template from https://git.ari.lt/templates/flask

Signed-off-by: Arija A. <ari@ari.lt>

src/app.py

@@ -0,0 +1,26 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""Flask app example"""
+
+from warnings import filterwarnings as filter_warnings
+
+from flask import Flask
+
+from flask_app import create_app
+
+app: Flask = create_app(__name__)
+
+
+def main() -> int:
+    """entry/main function"""
+
+    app.run("127.0.0.1", 8080, True)
+
+    return 0
+
+
+if __name__ == "__main__":
+    assert main.__annotations__.get("return") is int, "main() should return an integer"
+
+    filter_warnings("error", category=Warning)
+    raise SystemExit(main())