Updated the PHP version to 8.1 (resolved issue with dependencies)

If you try to run "composer install" from the shell with php v.8.0 you receive this error:

Your requirements could not be resolved to an installable set of packages.

Problem 1

Root composer.json requires monolog/monolog ^3 -> satisfiable by monolog/monolog[3.0.0, ..., 3.3.1].
monolog/monolog[3.0.0, ..., 3.3.1] require php >=8.1 -> your php version (8.0.27) does not satisfy that requirement. Problem 2
symfony/dotenv[v6.1.0, ..., v6.2.5] require php >=8.1 -> your php version (8.0.27) does not satisfy that requirement.
Root composer.json requires symfony/dotenv ^6.1 -> satisfiable by symfony/dotenv[v6.1.0, v6.1.11, v6.2.0, v6.2.5].

odan / slim4-skeleton