chore: remove version definition in composer.json

[samsonasik]

version in composer.json is not recommended by composer validate command

➜  ci4-pages git:(main) composer validate
./composer.json is valid, but with a few warnings
See https://getcomposer.org/doc/04-schema.md for details on the schema
# General warnings
- The version field is present, it is recommended to leave it out if the package is published on Packagist.

Also add gitHub actions step to validate it.

as composer.lock is not committed, on local, composer.lock can be regenerated:

composer update

[samsonasik]

@yllumi ready to merge 👍