ci: Only require approval for camera tests on fork PRs

'' is falsy in GitHub expressions, so the truthy branch of the
conditional environment never applied and every PR required approval.

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

Author: naushir

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

@@ -10,7 +10,10 @@ permissions:
 jobs:
   trigger-camera-tests:
     runs-on: [self-hosted, camera-test-bridge]
-    environment: ${{ github.event.pull_request.head.repo.full_name == github.repository && '' || 'camera-test' }}
+    # Fork PRs require manual approval through the camera-test environment.
+    # Note the condition must be inverted so that the truthy branch holds the
+    # non-empty string, as '' is falsy and would fall through to the || branch.
+    environment: ${{ github.event.pull_request.head.repo.full_name != github.repository && 'camera-test' || '' }}
     timeout-minutes: 120
     steps:
       - name: Checkout camera_tester