MT_RAND_PHP is used along with mt_srand to set a seed and make the values of mt_rand known for the tests, but it is deprecated in php8.3
Just using mt_srand without the parameter to use MT_RAND_MT19937 makes the test fail in php7.4 (and php8.1)
21) SamplingStatsdClientTest::testSampling with data set #0 (Liuggio\StatsdClient\Entity\StatsdData Object (...), 1, 0, true) Constant MT_RAND_PHP is deprecated /workspace/src/tests/phpunit/unit/includes/libs/SamplingStatsdClientTest.php:26 22) SamplingStatsdClientTest::testSampling with data set #1 (Liuggio\StatsdClient\Entity\StatsdData Object (...), 1, 0, false) Constant MT_RAND_PHP is deprecated /workspace/src/tests/phpunit/unit/includes/libs/SamplingStatsdClientTest.php:26 23) SamplingStatsdClientTest::testSampling with data set #2 (Liuggio\StatsdClient\Entity\StatsdData Object (...), 1, 4, true) Constant MT_RAND_PHP is deprecated /workspace/src/tests/phpunit/unit/includes/libs/SamplingStatsdClientTest.php:26 24) SamplingStatsdClientTest::testSampling with data set #3 (Liuggio\StatsdClient\Entity\StatsdData Object (...), 0.1, 0, false) Constant MT_RAND_PHP is deprecated /workspace/src/tests/phpunit/unit/includes/libs/SamplingStatsdClientTest.php:26 25) SamplingStatsdClientTest::testSampling with data set #4 (Liuggio\StatsdClient\Entity\StatsdData Object (...), 0.5, 0, false) Constant MT_RAND_PHP is deprecated /workspace/src/tests/phpunit/unit/includes/libs/SamplingStatsdClientTest.php:26 26) SamplingStatsdClientTest::testSampling with data set #5 (Liuggio\StatsdClient\Entity\StatsdData Object (...), 0.5, 4, false) Constant MT_RAND_PHP is deprecated