Update OP::Authentication to use uppercase headers

Signed-off-by: Alex Coles <alex@alexbcoles.com>

lib/open_project/authentication.rb

@@ -83,7 +83,7 @@ module OpenProject
       module_function
 
       def pick_auth_scheme(supported_schemes, default_scheme, request_headers = {})
-        req_scheme = request_headers['X-Authentication-Scheme']
+        req_scheme = request_headers['HTTP_X_AUTHENTICATION_SCHEME']
 
         if supported_schemes.include? req_scheme
           req_scheme

spec/controllers/api/v2/authentication_spec.rb

@@ -120,7 +120,7 @@ describe Api::V2::AuthenticationController, type: :controller do
 
     context 'with Session auth scheme requested' do
       before do
-        request.env['X-Authentication-Scheme'] = 'Session'
+        request.env['HTTP_X_AUTHENTICATION_SCHEME'] = 'Session'
       end
 
       it 'has Session auth scheme' do