Add Go 1.26 to GitHub Actions test matrix

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: appleboy

.github/workflows/testing.yml

@@ -13,7 +13,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        go: [1.24, 1.25]
+        go: [1.24, 1.25, 1.26]
     name: ${{ matrix.os }} @ Go ${{ matrix.go }}
     runs-on: ${{ matrix.os }}