Use mirador demo branch

package.json

@@ -37,7 +37,7 @@
     "@material-ui/icons": "^4.9.1",
     "@material-ui/lab": "^4.0.0-alpha.52",
     "lodash": "^4.17.11",
-    "mirador": "git+https://gitlab.tetras-libre.fr/lpo/mirador-video-annotations.git#gh3538-captions",
+    "mirador": "git+https://gitlab.tetras-libre.fr/lpo/mirador-video-annotations.git#demo_ci",
     "prop-types": "^15.7.2",
     "react": "^16.8",
     "react-dom": "^16.8",
@@ -66,7 +66,7 @@
     "jest-canvas-mock": "^2.2.0",
     "jest-junit": "^15.0.0",
     "jest-localstorage-mock": "^2.4.2",
-    "mirador": "git+https://gitlab.tetras-libre.fr/lpo/mirador-video-annotations.git#gh3538-captions",
+    "mirador": "git+https://gitlab.tetras-libre.fr/lpo/mirador-video-annotations.git#demo_ci",
     "nwb": "^0.24.7",
     "prop-types": "^15.7.2",
     "react": "^16.8",