ci: Add missing tmt installation for test-integration-cfs

The test-integration-cfs job was failing because it didn't have a step
to install tmt, unlike the regular test-integration jobs.

Assisted-by: Claude Code (Sonnet 4.5)

Author: cgwalters

.github/workflows/ci.yml

@@ -192,6 +192,8 @@ jobs:
         uses: ./.github/actions/bootc-ubuntu-setup
         with:
           libvirt: true
+      - name: Install tmt
+        run: pip install --user "tmt[provision-virtual]"
 
       - name: Build container
         run: just variant=composefs-sealeduki-sdboot build-integration-test-image