ci: rely on crates.io test network

Author: sanity

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

@@ -20,23 +20,13 @@ jobs:
         with:
           fetch-depth: 0
 
-      - name: Checkout freenet-test-network
-        uses: actions/checkout@v4
-        with:
-          repository: freenet/freenet-test-network
-          path: freenet-test-network
-
       - name: Checkout river
         uses: actions/checkout@v4
         with:
           repository: freenet/river
           ref: main
           path: river-src
 
-      - name: Link sibling dependencies
-        run: |
-          ln -sfn "${{ github.workspace }}/freenet-test-network" "${{ github.workspace }}/../freenet-test-network"
-
       - name: Install Rust
         uses: actions-rs/toolchain@v1
         with: