Add back the Docker::Version.correct? method

[Nishnha]

The #correct? method mimics creating a new Docker::Version without actually instantiating one. It checks that the semver part of the Docker::Version is actually valid semver.

The previous version of this method called #new and Docker::Version#new would call Gem::Version#new which would call #correct?, and it would get stuck in an infinite loop, so it was removed.

This PR adds in a working version of the method and there are already existing test cases for it like

dependabot-core/docker/spec/dependabot/docker/version_spec.rb

Lines 30 to 45 in 7cf0091

	describe ".correct?" do
	def check_version_for_correctness?(version)
	docker_version = described_class.new(version)
	described_class.correct?(docker_version)
	end
	it "classifies standard versions as correct" do
	expect(check_version_for_correctness?("2.4.2")).to be true
	end
	it "classifies java versions as correct" do
	expect(check_version_for_correctness?("11.0.16_8")).to be true
	expect(check_version_for_correctness?("v11.0.16_8")).to be true
	expect(check_version_for_correctness?("11.0.16.1")).to be true
	end
	end