feat(backend) avoid showing project that photo url is null (#195)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **New Features**
- Updated public projects listing to display only projects that include
a photo, ensuring a visually consistent experience for users.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: ZHallen122

backend/src/project/project.service.ts

@@ -7,7 +7,7 @@ import {
   ForbiddenException,
 } from '@nestjs/common';
 import { InjectRepository } from '@nestjs/typeorm';
-import { Between, In, Not, Repository } from 'typeorm';
+import { Between, In, IsNull, Not, Repository } from 'typeorm';
 import { Project } from './project.model';
 import { ProjectPackages } from './project-packages.model';
 import {
@@ -637,6 +637,7 @@ export class ProjectService {
     const whereCondition = {
       isPublic: true,
       isDeleted: false,
+      photoUrl: Not(IsNull()),
     };
 
     if (input.strategy === 'latest') {