composer.json: run `composer validate --strict`

[lkraav]

This allows us to catch

• strategical mistakes
• updates without composer.lock refresh

leho@papaya cxl-wpstarter.git $ [git:leho/feat/add-deployer+?{3}] ./composer validate --strict
./composer.json is valid, but with a few warnings
See https://getcomposer.org/doc/04-schema.md for details on the schema
# General warnings
- No license specified, it is recommended to do so. For closed-source software you may use "proprietary" as license.
- require.cxl/accredible-certificates : exact version constraints (1.4.8) should be avoided if the package follows semantic versioning
- ...