chore(*): fixing the tests build

Author: kdinev

projects/igniteui-angular/src/lib/grids/pivot-grid/pivot-grid.spec.ts

@@ -1,7 +1,7 @@
 import { ComponentFixture, fakeAsync, TestBed, tick, waitForAsync } from '@angular/core/testing';
 import { By } from '@angular/platform-browser';
 import { NoopAnimationsModule } from '@angular/platform-browser/animations';
-import { FilteringExpressionsTree, FilteringLogic, GridColumnDataType, IgxPivotGridComponent, IgxPivotRowDimensionHeaderGroupComponent, IgxStringFilteringOperand } from 'igniteui-angular';
+import { FilteringExpressionsTree, FilteringLogic, GridColumnDataType, IgxPivotGridComponent, IgxStringFilteringOperand } from 'igniteui-angular';
 import { IgxChipComponent } from '../../chips/chip.component';
 import { IgxChipsAreaComponent } from '../../chips/chips-area.component';
 import { DefaultPivotSortingStrategy } from '../../data-operations/pivot-sort-strategy';
@@ -18,6 +18,7 @@ import { IPivotGridColumn, IPivotGridRecord, PivotDimensionType } from './pivot-
 import { IgxPivotHeaderRowComponent } from './pivot-header-row.component';
 import { IgxPivotRowDimensionHeaderComponent } from './pivot-row-dimension-header.component';
 import { IgxPivotRowComponent } from './pivot-row.component';
+import { IgxPivotRowDimensionHeaderGroupComponent } from './pivot-row-dimension-header-group.component';
 
 const CSS_CLASS_LIST = 'igx-drop-down__list';
 const CSS_CLASS_ITEM = 'igx-drop-down__item';