OZG-6477 small fix

alfa-client/libs/collaboration-shared/src/lib/collaboration.model.ts

@@ -5,12 +5,12 @@ export interface Collaboration {
   titel: string;
   beschreibung: string;
   zustaendigeStelle: ResourceUri;
-  collaborationLevel?: typeof CollaborationLevels[keyof typeof CollaborationLevels];
+  collaborationLevel?: (typeof CollaborationLevels)[keyof typeof CollaborationLevels];
 }
 
 export class CollaborationLevels {
-  public static readonly ORGANISATIONS_EINHEIT = "1";
-  public static readonly EXTERNE_FACHSTELLE = "4";
+  public static readonly ORGANISATIONS_EINHEIT = 1;
+  public static readonly EXTERNE_FACHSTELLE = 4;
 }
 
 export interface CollaborationResource extends Collaboration, Resource, ListItemResource {}