/usr/share/php/GuzzleHttp/Psr7/ is in php-guzzlehttp-psr7 1.2.2-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/php/GuzzleHttp/Psr7/AppendStream.php
/usr/share/php/GuzzleHttp/Psr7/BufferStream.php
/usr/share/php/GuzzleHttp/Psr7/CachingStream.php
/usr/share/php/GuzzleHttp/Psr7/DroppingStream.php
/usr/share/php/GuzzleHttp/Psr7/FnStream.php
/usr/share/php/GuzzleHttp/Psr7/InflateStream.php
/usr/share/php/GuzzleHttp/Psr7/LazyOpenStream.php
/usr/share/php/GuzzleHttp/Psr7/LimitStream.php
/usr/share/php/GuzzleHttp/Psr7/MessageTrait.php
/usr/share/php/GuzzleHttp/Psr7/MultipartStream.php
/usr/share/php/GuzzleHttp/Psr7/NoSeekStream.php
/usr/share/php/GuzzleHttp/Psr7/PumpStream.php
/usr/share/php/GuzzleHttp/Psr7/Request.php
/usr/share/php/GuzzleHttp/Psr7/Response.php
/usr/share/php/GuzzleHttp/Psr7/Stream.php
/usr/share/php/GuzzleHttp/Psr7/StreamDecoratorTrait.php
/usr/share/php/GuzzleHttp/Psr7/StreamWrapper.php
/usr/share/php/GuzzleHttp/Psr7/Uri.php
/usr/share/php/GuzzleHttp/Psr7/autoload.php
/usr/share/php/GuzzleHttp/Psr7/functions.php
/usr/share/php/GuzzleHttp/Psr7/functions_include.php