fix: Use browserslist-config

We were installing browserslist-config but not declaring it.  This had
the effect that webpack - and likely others - were not using it.

package.json

@@ -6,6 +6,9 @@
     "type": "git",
     "url": "git+https://github.com/edx/frontend-app-learner-dashboard.git"
   },
+  "browserslist": [
+    "extends @edx/browserslist-config"
+  ],
   "scripts": {
     "build": "fedx-scripts webpack",
     "i18n_extract": "fedx-scripts formatjs extract",
@@ -27,7 +30,7 @@
   },
   "dependencies": {
     "@edx/brand": "npm:@openedx/brand-openedx@^1.2.2",
-    "@edx/browserslist-config": "^1.1.0",
+    "@edx/browserslist-config": "^1.3.0",
     "@edx/frontend-component-header": "^5.6.0",
     "@edx/frontend-enterprise-hotjar": "7.1.0",
     "@edx/frontend-platform": "8.1.2",