test against multiple versions of Go

update dependabot to include GH actions

.github/dependabot.yml

@@ -9,3 +9,7 @@ updates:
     directory: "/" # Location of package manifests
     schedule:
       interval: "weekly"
+  - package-ecosystem: "github-actions" # See documentation for possible values
+    directory: "/" # Location of package manifests
+    schedule:
+      interval: "weekly"

.github/workflows/go.yml

@@ -13,13 +13,16 @@ jobs:
 
   build:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        go-version: ["1.21", "1.22", "1.23"]
     steps:
     - uses: actions/checkout@v4
 
     - name: Set up Go
       uses: actions/setup-go@v4
       with:
-        go-version: '1.21'
+        go-version: ${{ matrix.go-version }}
 
     - name: Build
       run: go build -v ./...