Link costing based on average RTT (#1171)

This PR updates Ironwood to include the new RTT-based link costing and
updates `yggdrasilctl` to report the cost in `getPeers`.

Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>

.github/workflows/ci.yml

@@ -17,10 +17,10 @@ jobs:
     steps:
       - uses: actions/setup-go@v5
         with:
-          go-version: 1.21
+          go-version: stable
       - uses: actions/checkout@v4
       - name: golangci-lint
-        uses: golangci/golangci-lint-action@v3
+        uses: golangci/golangci-lint-action@v6
         with:
           args: --issues-exit-code=1
 
@@ -51,7 +51,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        goversion: ["1.21", "1.22"]
+        goversion: ["1.21", "1.22", "1.23"]
 
     name: Build & Test (Linux, Go ${{ matrix.goversion }})
     needs: [lint]
@@ -75,7 +75,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        goversion: ["1.21", "1.22"]
+        goversion: ["1.21", "1.22", "1.23"]
 
     name: Build & Test (Windows, Go ${{ matrix.goversion }})
     needs: [lint]
@@ -99,7 +99,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        goversion: ["1.21", "1.22"]
+        goversion: ["1.21", "1.22", "1.23"]
 
     name: Build & Test (macOS, Go ${{ matrix.goversion }})
     needs: [lint]
@@ -123,7 +123,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        goversion: ["1.21", "1.22"]
+        goversion: ["1.21", "1.22", "1.23"]
         goos:
           - freebsd
           - openbsd