fix: Ensure newline at end of file in address_validation.py and update news fragment formatting

Author: yashksaini-coder

libp2p/utils/address_validation.py

@@ -147,4 +147,4 @@ def is_non_loopback(ma: Multiaddr) -> bool:
     "get_available_interfaces",
     "get_optimal_binding_address",
     "expand_wildcard_address",
-]
+]

newsfragments/811.internal.rst

@@ -4,4 +4,4 @@ Add Thin Waist address validation utilities and integrate into echo example
 - Implement ``get_available_interfaces()``, ``get_optimal_binding_address()``, and ``expand_wildcard_address()``
 - Update echo example to use dynamic address discovery instead of hardcoded wildcard
 - Add safe fallbacks for environments lacking Thin Waist support
-- Temporarily disable IPv6 support due to libp2p handshake issues (TODO: re-enable when resolved)
+- Temporarily disable IPv6 support due to libp2p handshake issues (TODO: re-enable when resolved)