fix: update fixedPlaceholder default value to true in NgSelectConfig

Author: pavankjadda

src/ng-select/lib/config.service.ts

@@ -3,7 +3,7 @@ import { Injectable } from '@angular/core';
 @Injectable({ providedIn: 'root' })
 export class NgSelectConfig {
 	placeholder: string;
-	fixedPlaceholder = false;
+	fixedPlaceholder = true;
 	notFoundText = 'No items found';
 	typeToSearchText = 'Type to search';
 	addTagText = 'Add item';

src/ng-select/lib/ng-select.component.spec.ts

@@ -2606,7 +2606,7 @@ describe('NgSelectComponent', () => {
 
 			expect(fixture.debugElement.query(By.css('.ng-placeholder'))).toBeFalsy();
 		}));
-
+		
 		it('should update ng-option label', fakeAsync(() => {
 			const fixture = createTestingModule(
 				NgSelectTestComponent,

src/ng-select/lib/ng-select.component.ts

@@ -90,7 +90,7 @@ export class NgSelectComponent implements OnDestroy, OnChanges, OnInit, AfterVie
 	@Input() ariaLabel: string | undefined;
 	@Input({ transform: booleanAttribute }) markFirst = true;
 	@Input() placeholder: string;
-	@Input() fixedPlaceholder: boolean = false;
+	@Input() fixedPlaceholder: boolean = true;
 	@Input() notFoundText: string;
 	@Input() typeToSearchText: string;
 	@Input() preventToggleOnRightClick: boolean = false;