Update map.service.ts (#408)

fixing es-build angular 16 build with error
```
Cannot assign to import "baseApiUrl"

    node_modules/ngx-mapbox-gl/fesm2022/ngx-mapbox-gl.mjs:34:25:
      34 │                 MapboxGl.baseApiUrl = options.customMapboxApiUrl;
         ╵                          ~~~~~~~~~~

  Imports are immutable in JavaScript. To modify the value of this import
```
related to evanw/esbuild#891,



fixes:
#403
#407

libs/ngx-mapbox-gl/src/lib/map/map.service.ts

@@ -6,7 +6,7 @@ import {
  NgZone,
  Optional,
 } from '@angular/core';
-import * as MapboxGl from 'mapbox-gl';
+import MapboxGl from 'mapbox-gl';
 import { AsyncSubject, Observable, Subscription } from 'rxjs';
 import { first } from 'rxjs/operators';
 import {