Update README.md

README.md

@@ -29,6 +29,10 @@ It is used in [Yii Framework] but is supposed to be usable separately.
 |[[db-pgsql]](https://github.com/yiisoft/db-pgsql)|**7.4 - 8.0**| **9.0 - 15.0**|[![Build status](https://github.com/yiisoft/db-pgsql/workflows/build/badge.svg)](https://github.com/yiisoft/db-pgsql/actions?query=workflow%3Abuild) [![Mutation testing badge](https://img.shields.io/endpoint?style=flat&url=https%3A%2F%2Fbadge-api.stryker-mutator.io%2Fgithub.com%2Fyiisoft%2Fdb-pgsql%2Fmaster)](https://dashboard.stryker-mutator.io/reports/github.com/yiisoft/db-pgsql/master) [![codecov](https://codecov.io/gh/yiisoft/db-pgsql/branch/master/graph/badge.svg?token=3FGN91IVZA)](https://codecov.io/gh/yiisoft/db-pgsql)|
 |[[db-sqlite]](https://github.com/yiisoft/db-sqlite)|**7.4 - 8.0**| **3:latest**|[![Build status](https://github.com/yiisoft/db-sqlite/workflows/build/badge.svg)](https://github.com/yiisoft/db-sqlite/actions?query=workflow%3Abuild) [![Mutation testing badge](https://img.shields.io/endpoint?style=flat&url=https%3A%2F%2Fbadge-api.stryker-mutator.io%2Fgithub.com%2Fyiisoft%2Fdb-sqlite%2Fmaster)](https://dashboard.stryker-mutator.io/reports/github.com/yiisoft/db-sqlite/master) [![codecov](https://codecov.io/gh/yiisoft/db-sqlite/branch/master/graph/badge.svg?token=YXUHCPPITH)](https://codecov.io/gh/yiisoft/db-sqlite)|
 
+## Requirements
+
+- PHP 8.1 or higher.
+
 ## Installation
 
 The package could be installed via composer: