ci: Allow CI to run on the next branch and on forked repos

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>

Author: naushir

.github/workflows/camera-test-picamera2.yml

@@ -2,16 +2,14 @@ name: Camera Tests
 
 on:
   pull_request_target:
-    branches: [main]
+    branches: [main, next]
 
 permissions:
   statuses: write
 
 jobs:
   trigger-camera-tests:
     runs-on: [self-hosted, camera-test-bridge]
-    if: >-
-      github.event.pull_request.head.repo.full_name == github.repository
     timeout-minutes: 120
     steps:
       - name: Checkout camera_tester