Update test-pr.yml (#1471)

* Update test-pr.yml

* Testing PRIVATE_TOKEN already generated

* Reverting to new RV PRivate CACHIX Key

Author: F-WRunTime

.github/workflows/test-pr.yml

@@ -142,6 +142,7 @@ jobs:
           name: runtimeverification
           extraPullNames: kore
           signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
+          authToken: ${{ secrets.CACHIX_RV_PRIVATE_TOKEN }}
 
       # - name: Check submodules
       #   run: GC_DONT_GC=1 nix run .#check-submodules