fix(filters): invalid filter range when converting dates to strings

Resolves https://community.vikunja.io/t/my-vikunja-instance-creates-tasks-with-due-date-time-of-9am-for-tasks-with-the-word-today-word-in-it/2105/10

frontend/src/services/taskCollection.ts

@@ -4,7 +4,7 @@ import TaskModel from '@/models/task'
 import type {ITask} from '@/modelTypes/ITask'
 
 export interface TaskFilterParams {
-	sort_by: ('start_date' | 'done' | 'id' | 'position' | 'kanban_position')[],
+	sort_by: ('start_date' | 'end_date' | 'due_date' | 'done' | 'id' | 'position' | 'kanban_position')[],
 	order_by: ('asc' | 'desc')[],
 	filter: string,
 	filter_include_nulls: boolean,

frontend/src/views/tasks/ShowTasks.vue

@@ -173,7 +173,7 @@ function setShowNulls(show: boolean) {
 	})
 }
 
-async function loadPendingTasks(from: string, to: string) {
+async function loadPendingTasks(from: Date|string, to: Date|string) {
 	// FIXME: HACK! This should never happen.
 	// Since this route is authentication only, users would get an error message if they access the page unauthenticated.
 	// Since this component is mounted as the home page before unauthenticated users get redirected
@@ -187,16 +187,18 @@ async function loadPendingTasks(from: string, to: string) {
 		order_by: ['asc', 'desc'],
 		filter: 'done = false',
 		filter_include_nulls: showNulls,
+		s: '',
 	}
 
 	if (!showAll.value) {
-		params.filter += ` && due_date < '${to}'`
+		
+		params.filter += ` && due_date < '${to instanceof Date ? to.toISOString() : to}'`
 
 		// NOTE: Ideally we could also show tasks with a start or end date in the specified range, but the api
 		//       is not capable (yet) of combining multiple filters with 'and' and 'or'.
 
 		if (!showOverdue) {
-			params.filter += ` && due_date > '${from}'`
+			params.filter += ` && due_date > '${from instanceof Date ? from.toISOString() : from}'`
 		}
 	}