ci: checkout freenet-core at workspace root

Author: sanity

.github/workflows/six-peer-regression.yml

@@ -19,7 +19,6 @@ jobs:
         uses: actions/checkout@v4
         with:
           fetch-depth: 0
-          path: freenet-core
 
       - name: Checkout river
         uses: actions/checkout@v4
@@ -36,9 +35,9 @@ jobs:
           override: true
 
       - name: Run six-peer regression
-        working-directory: ${{ github.workspace }}/river/main
+        working-directory: river/main
         env:
-          FREENET_CORE_PATH: ${{ github.workspace }}/freenet-core
+          FREENET_CORE_PATH: ${{ github.workspace }}
           RUST_LOG: info
         run: |
           cargo test --test message_flow river_message_flow_over_freenet_six_peers_five_rounds -- --ignored --exact