fixed dropdown

src/app/appmarket/appinstance/appinstance/appinstance.component.css

@@ -78,4 +78,7 @@
 :host ::ng-deep  .p-dropdown {
     width: 200px;
 }
-
+.ui-dropdown-panel {
+    max-height: 150px;
+    overflow-y: auto;
+}

src/app/appmarket/appinstance/appinstance/appinstance.component.html

@@ -224,7 +224,7 @@
             <h4 style="text-align: center">{{'APP_INSTANCES.MANUAL_UPDATE.HEADER' | translate}}</h4>
         </div>
         <div class="nmaas-modal-body">
-            <div class="" style="height: 150px">
+            <div class="" style="height: 250px">
                 <p>{{'APP_INSTANCES.MANUAL_UPDATE.BODY' | translate}}</p>
                 <div *ngIf="appVersions.length > 0">
                     <p-dropdown id="manualUpdate" [options]="appVersions" optionLabel="version" optionValue="version"