Bump actions/setup-go from 5 to 6 (closes #2)

Change-Id: Ieefb951b9d34080e0f0dd82898a2177ded3d4cda
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index de1779d..24eb799 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -19,7 +19,7 @@
       - uses: actions/checkout@v4
 
       - name: Set up Go ${{ matrix.go-version }}
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v6
         with:
           go-version: ${{ matrix.go-version }}