chore(calendar): update DayDigitPipe paths

- Updated `DayDigitPipe` import paths to use relative paths.

Author: desig9stein

projects/igniteui-angular/calendar/src/calendar/day-digit.pipe.ts

@@ -1,5 +1,5 @@
 import { Pipe, PipeTransform } from '@angular/core';
-import { IFormattingViews } from "igniteui-angular/calendar";
+import { IFormattingViews } from "./calendar";
 
 @Pipe({ name: 'dayDigit' })
 export class DayDigitPipe implements PipeTransform {

projects/igniteui-angular/calendar/src/calendar/days-view/days-view.component.ts

@@ -37,7 +37,7 @@ import {
 import { IgxCalendarBaseDirective } from '../calendar-base';
 import { IViewChangingEventArgs } from './days-view.interface';
 import { KeyboardNavigationService } from '../calendar.services';
-import { DayDigitPipe } from "igniteui-angular/calendar/src/calendar/day-digit.pipe";
+import { DayDigitPipe } from "../day-digit.pipe";
 
 let NEXT_ID = 0;