Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires phpunit/phpunit 6.3.1 -> satisfiable by phpunit/phpunit[6.3.1]. - phpunit/phpunit 6.3.1 requires php ^7.0 -> your php version (5.6.40) does not satisfy that requirement. Problem 2 - yoast/phpunit-polyfills 2.0.0 requires phpunit/phpunit ^5.7.21 || ^6.0 || ^7.0 || ^8.0 || ^9.0 || ^10.0 -> satisfiable by phpunit/phpunit[6.3.1]. - yoast/phpunit-polyfills[0.2.0, 1.0.0, ..., 1.0.5] require phpunit/phpunit ^4.8.36 || ^5.7.21 || ^6.0 || ^7.0 || ^8.0 || ^9.0 -> satisfiable by phpunit/phpunit[6.3.1]. - yoast/phpunit-polyfills 0.1.0 requires phpunit/phpunit ^5.7 || ^6.0 || ^7.0 || ^8.0 || ^9.0 -> satisfiable by phpunit/phpunit[6.3.1]. - phpunit/phpunit 6.3.1 requires php ^7.0 -> your php version (5.6.40) does not satisfy that requirement. - Root composer.json requires yoast/phpunit-polyfills * -> satisfiable by yoast/phpunit-polyfills[0.1.0, 0.2.0, 1.0.0, ..., 1.0.5, 2.0.0].

Process completed with exit code 2.

Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires phpunit/phpunit 6.3.1 -> satisfiable by phpunit/phpunit[6.3.1]. - phpunit/phpunit 6.3.1 requires php ^7.0 -> your php version (5.6.40) does not satisfy that requirement. Problem 2 - yoast/phpunit-polyfills 2.0.0 requires phpunit/phpunit ^5.7.21 || ^6.0 || ^7.0 || ^8.0 || ^9.0 || ^10.0 -> satisfiable by phpunit/phpunit[6.3.1]. - yoast/phpunit-polyfills[0.2.0, 1.0.0, ..., 1.0.5] require phpunit/phpunit ^4.8.36 || ^5.7.21 || ^6.0 || ^7.0 || ^8.0 || ^9.0 -> satisfiable by phpunit/phpunit[6.3.1]. - yoast/phpunit-polyfills 0.1.0 requires phpunit/phpunit ^5.7 || ^6.0 || ^7.0 || ^8.0 || ^9.0 -> satisfiable by phpunit/phpunit[6.3.1]. - phpunit/phpunit 6.3.1 requires php ^7.0 -> your php version (5.6.40) does not satisfy that requirement. - Root composer.json requires yoast/phpunit-polyfills * -> satisfiable by yoast/phpunit-polyfills[0.1.0, 0.2.0, 1.0.0, ..., 1.0.5, 2.0.0].

Process completed with exit code 2.

The job was canceled because "_5_6_6_3_1_5_8_" failed.

A task was canceled.

The job was canceled because "_5_6_6_3_1_5_8_" failed.

Process completed with exit code 2.

The job was canceled because "_5_6_6_3_1_5_8_" failed.

The operation was canceled.

The job was canceled because "_5_6_6_3_1_5_8_" failed.

The operation was canceled.

The job was canceled because "_5_6_6_3_1_5_8_" failed.

Process completed with exit code 255.

The job was canceled because "_5_6_6_3_1_5_8_" failed.

The operation was canceled.

The operation was canceled.

The job was canceled because "_5_6_6_3_1_5_8_" failed.

The operation was canceled.

The job was canceled because "_5_6_6_3_1_5_8_" failed.

The operation was canceled.

The operation was canceled.

The job was canceled because "_5_6_6_3_1_5_8_" failed.

The operation was canceled.

The job was canceled because "_5_6_6_3_1_5_8_" failed.

The operation was canceled.

The operation was canceled.

The operation was canceled.

The job was canceled because "_5_6_6_3_1_5_8_" failed.

The operation was canceled.

The job was canceled because "_5_6_6_3_1_5_8_" failed.