v1.31.0

Added

Native e-mail / SMTP notifications (#2). A real e-mail channel alongside Telegram, Discord and generic webhooks — for "updates available", update results, and other notifications.

Configure with SMTP_HOST + SMTP_FROM + SMTP_TO (plus optional SMTP_PORT, SMTP_USER, SMTP_PASSWORD, SMTP_TLS):

• SMTP_TLS = starttls (default, 587), ssl (implicit TLS, 465), or none (plain/relay)
• SMTP_TO accepts a comma-separated list
• BOT_LABEL is applied to the subject so multi-host setups stay distinguishable

Built on the standard library (smtplib) — no new dependency — respects quiet hours / maintenance like the other channels, and sends best-effort (failures are logged, never crash an update).