fix: missing @popperjs/core peer dependency

Author: sinedied

generators/app/templates/_package.json

@@ -102,6 +102,7 @@
     "@ionic/angular": "^6.0.0",
 <% } else if (props.ui === 'bootstrap') { -%>
     "@ng-bootstrap/ng-bootstrap": "^12.0.0-beta.4",
+    "@popperjs/core": "^2.11.0",
     "bootstrap": "^5.0.2",
     "@fortawesome/fontawesome-free": "^5.15.1",
 <% } else if (props.ui === 'material') { -%>