refactor: remove unnecessary type conversion failing lint

I suspect there were some versioning changes with the e.g. `hoist =
false` setting in npmrc; so eslint now starts failing about this
unnessary type cast. Seems reasonable so this is committed without
deep investigation.

packages/angular_devkit/build_angular/src/builders/dev-server/webpack-server.ts

@@ -263,7 +263,7 @@ export function serveWebpackBrowser(
             ...buildEvent,
             baseUrl: serverAddress,
             stats: generateBuildEventStats(webpackRawStats, browserOptions),
-          } as DevServerBuilderOutput;
+          };
         }),
       );
     }),