docs: update changelog

Signed-off-by: Roman Ondráček <mail@romanondracek.cz>

Author: Roman3349

CHANGELOG.md

@@ -5,6 +5,7 @@
 1. [#171](https://github.com/influxdata/influxdb-client-php/pull/171): Bring CI pipeline up to date.
    - Remove PHP 7.2 from CI build.
    - Add PHP 8.5 to CI build.
+2. [#172](https://github.com/influxdata/influxdb-client-php/pull/172): Suggest dependency on `ext-sockets` for `InfluxDB2\UdpWriter`.
 
 ## 3.8.0 [2026-06-26]