Add invoke as task runner, ruff and fix mypy errors

scripts/smtp-send-test-email.py

@@ -16,11 +16,11 @@ import sys
 from email.message import EmailMessage
 
 
-def send_test_email(login, password, to_email):
+def send_test_email(login: str, password: str, to_email: str) -> None:
     """Отправляет тестовое email через Yandex Cloud Postbox SMTP"""
 
     # initialize connection to our email server
-    smtp = smtplib.SMTP("postbox.cloud.yandex.net", port="587")
+    smtp = smtplib.SMTP("postbox.cloud.yandex.net", port=587)
 
     smtp.set_debuglevel(2)
 
@@ -43,7 +43,7 @@ def send_test_email(login, password, to_email):
     print(f"Test email successfully sent to {to_email}")
 
 
-def main():
+def main() -> None:
     parser = argparse.ArgumentParser(
         description="Send a test email via Yandex Cloud Postbox SMTP server."
     )