- root composer.json requires php ^7.1.3 but your php version (8.0.3) does not satisfy that requirement.
It's becouse in your project in composer.json file you have:
"require": {
"php": ">=7.3",
.....
},
Try to update this requirement to:
"require": {
"php": "^7.3|^8.0",
.....
},