.github: set SITL_PANIC_EXIT in Copter test suite

CI can hang for 30 minutes if we panic

Author: peterbarker

.github/workflows/test_sitl_copter.yml

@@ -209,6 +209,7 @@ jobs:
     container:
       image: ardupilot/ardupilot-dev-base:v0.1.3
       options: --privileged --cap-add=SYS_PTRACE --security-opt apparmor=unconfined --security-opt seccomp=unconfined
+    env: SITL_PANIC_EXIT: 1
     strategy:
       fail-fast: false  # don't cancel if a job from the matrix fails
       matrix: