update fixture as NGA one has a cert issue

__tests__/integration/mirador/index.html

@@ -17,7 +17,7 @@
          canvasIndex: 2,
        },
        {
-         loadedManifest: 'https://media.nga.gov/public/manifests/nga_highlights.json',
+         loadedManifest: 'https://iiif.bodleian.ox.ac.uk/iiif/manifest/e32a277e-91e2-4a6d-8ba6-cc4bad230410.json',
          thumbnailNavigationPosition: 'off',
        }]
      });