Update dependency macos to v26

Author: renovate[bot]

.github/workflows/ci.yaml

@@ -113,7 +113,7 @@ jobs:
 
   build-cgo-macos:
     name: Build (macOS CGO)
-    runs-on: macos-15
+    runs-on: macos-26
     steps:
       - name: Checkout repository
         uses: actions/checkout@v6