ci: Set freebsd to timeout after 30min

The job runs very unreliably and often times out after 6h of being stuck
in a boot loop.
This commit reduces the timeout to 30min.

.github/workflows/freebsd.yml

@@ -12,6 +12,7 @@ jobs:
     - uses: actions/checkout@v3
     - name: Test in FreeBSD VM
       uses: vmactions/freebsd-vm@v0
+      timeout-minutes: 30
       with:
         mem: 2048
         usesh: true