Add missing RSpec module references to initial describe calls

Author: anakinj

spec/jwt/jwk/okp_rbnacl_spec.rb

@@ -2,7 +2,7 @@
 
 require 'securerandom'
 
-describe 'JWT::JWK::OKPRbNaCl' do
+RSpec.describe 'JWT::JWK::OKPRbNaCl' do
   let(:described_class) { JWT::JWK::OKPRbNaCl }
   let(:private_key) { RbNaCl::Signatures::Ed25519::SigningKey.new(SecureRandom.hex) }
   let(:public_key)  { private_key.verify_key }

spec/jwt/x5c_key_finder_spec.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-describe JWT::X5cKeyFinder do
+RSpec.describe JWT::X5cKeyFinder do
   let(:root_key) { test_pkey('rsa-2048-private.pem') }
   let(:root_dn) { OpenSSL::X509::Name.parse('/DC=org/DC=fake-ca/CN=Fake CA') }
   let(:root_certificate) { generate_root_cert(root_dn, root_key) }