ui-vintage: bootstrap install doesn't work as documented

[nicolasduminil]

Trying to install bootstrap as documented in README.md doesn't work, as shown below:

$ ng add @ng-bootstrap/ng-bootstrap@bootstrap5
ℹ Using package manager: npm
✖ Unable to fetch package information for '@ng-bootstrap/ng-bootstrap@bootstrap5': No matching version found for @ng-  bootstrap/ng-bootstrap@bootstrap5.

Using angular 16.2.2

$ ng version

Angular CLI: 16.2.2
Node: 18.18.0
Package Manager: npm 9.8.1
OS: linux x64

Angular: 16.2.5
... animations, common, compiler, compiler-cli, core, forms
... localize, platform-browser, platform-browser-dynamic, router

Package                         Version
--------------------------------------------------------- 
@angular-devkit/architect       0.1602.2
@angular-devkit/build-angular   16.2.2
@angular-devkit/core            16.2.2
@angular-devkit/schematics      16.2.2
@angular/cli                    16.2.2
@schematics/angular             16.2.2
rxjs                            7.8.1
typescript                      5.1.6
zone.js                         0.13.3