Update CI OS versions in readme

Author: andyleejordan

README.md

@@ -64,8 +64,9 @@ The extension should work everywhere [Visual Studio Code](https://code.visualstu
 [VS Code Remote Development](https://code.visualstudio.com/docs/remote/remote-overview) Environments, including [Github Codespaces](https://github.com/features/codespaces) and [VS Code Server](https://code.visualstudio.com/docs/remote/vscode-server) are supported.
 
 We actively test the following configurations [in Github Actions on every commit](https://github.com/PowerShell/vscode-powershell/actions/workflows/ci-test.yml):
-- **Windows Server 2022** with Windows PowerShell 5.1 and PowerShell 7+
-- **macOS 14.7** with PowerShell 7+
+
+- **Windows Server 2025** with Windows PowerShell 5.1 and PowerShell 7+
+- **macOS 15.7.1** with PowerShell 7+
 - **Ubuntu 24.04** with PowerShell 7+
 
 On Windows, we also test with and without Constrained Language Mode enabled.