fix: use the plural repo name for the GitHub Pages baseHref

The demo deploys under https://muuvmuuv.github.io/angular-extended-builders/
(the repository name is plural), but the github-pages build used the singular
/angular-extended-builder/ baseHref, so every asset returned 404. Match it to
the repository path.

Author: muuvmuuv

projects/app/angular.json

@@ -35,7 +35,7 @@
 						"github-pages": {
 							"subresourceIntegrity": true,
 							"outputHashing": "all",
-							"baseHref": "/angular-extended-builder/"
+							"baseHref": "/angular-extended-builders/"
 						},
 						"development": {
 							"optimization": false,