How to update Laravel composer.json

I included "tymon/jwt-auth" : "~1.0.0-rc.2" in my composer.json file. and when i run composer update, it returns the following errors: Cannot create cache directory /home/mpete/.composer/cache/repo/https---packagist.org/, or directory is not writable. Proceeding without cache Cannot create cache directory /home/mpete/.composer/cache/files/, or directory is not writable. Proceeding without cache

"require": { "php": "^7.1.3", "fideloper/proxy": "^4.0", "laravel/framework": "5.8.*", "laravel/tinker": "^1.0", "tymon/jwt-auth" : "~1.0.0-rc.2" }enter image description here

via Chebli Mohamed