chore: bump GitHub Actions to Node.js 24 versions

checkout v4→v6, setup-go v5→v6, goreleaser-action v6→v7.
Node.js 20 actions are deprecated and will stop working Sep 2026.

Author: brianm

.github/workflows/build.yml

@@ -13,10 +13,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Set up Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v6
         with:
           go-version-file: go.mod
 

.github/workflows/release.yml

@@ -14,20 +14,20 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
 
       - name: Set up Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v6
         with:
           go-version-file: go.mod
 
       - name: Test
         run: make test
 
       - name: Run goreleaser
-        uses: goreleaser/goreleaser-action@v6
+        uses: goreleaser/goreleaser-action@v7
         with:
           version: "~> v2"
           args: release --clean
@@ -40,7 +40,7 @@ jobs:
     needs: release
     steps:
       - name: Check out code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Build package in FreeBSD VM
         uses: vmactions/freebsd-vm@v1