Add missing identity provider: gitlab

[Knerio]

code0-identities/lib/code0/identities.rb

Lines 6 to 15 in c924e29

	require_relative "identities/version"
	require_relative "identities/identity_provider"
	require_relative "identities/identity"
	require_relative "identities/provider/base_oauth"
	require_relative "identities/provider/microsoft"
	require_relative "identities/provider/google"
	require_relative "identities/provider/discord"
	require_relative "identities/provider/github"
	require_relative "identities/provider/oidc"
	require_relative "identities/provider/saml"