webpack: precache oss-licenses.json

This works around the oss-licenses.json file not being picked up by
the workbox plugin.

Closes: https://github.com/pybricks/pybricks-code/issues/1245

config/webpack.config.js

@@ -726,6 +726,10 @@ module.exports = function (webpackEnv) {
           // to make lazy-loading failure scenarios less likely.
           // See https://github.com/cra-template/pwa/issues/13#issuecomment-722667270
           maximumFileSizeToCacheInBytes: 10 * 1024 * 1024,
+          additionalManifestEntries: [
+            // FIXME: this path should have a hash
+            { url: 'static/oss-licenses.json', revision: null },
+          ],
         }),
       // TypeScript type checking
       useTypeScript &&