feat!: use a different JSON schema validator

[jkowalleck]

currently using opis/json-schema - https://packagist.org/packages/opis/json-schema

let's switch to a more popular JSON schema validator: justinrainbow/json-schema - https://packagist.org/packages/justinrainbow/json-schema

this is considered a breaking change, as such a switch might introduce unintended issues with schema validation.

[jkowalleck]

A PHP Implementation for validating JSON Structures against a given Schema with support for Schemas of Draft-3, Draft-4 or Draft-6.

Features of newer Drafts might not be supported. See Table of All Versions of Everything to get an overview of all existing Drafts. See json-schema for more details about the JSON Schema specification

need to validate if this lib is capable to do the job here.

[jkowalleck]

let's switch to a more popular JSON schema validator: justinrainbow/json-schema - https://packagist.org/packages/justinrainbow/json-schema

postponed for

cyclonedx-php-library/docs/dev/decisions/JsonSchemaValidator.md

Lines 9 to 20 in b248039

	## Option: [justinrainbow/json-schema]
	CONS:
	* -> Does not claim fully to support _draft7_ - which is needed for CDX schema.
	* Is shipped with composer v2.0 as `^5.2.10`.
	-> Which might lead to conflicts in the composer plugin, if we are using a newer version.
	PROS:
	* php: >=5.3.3
	* No further dependencies