github: add macos-26

Author: aconchillo

.github/workflows/tests.yml

@@ -10,7 +10,7 @@ jobs:
   test-bot:
     strategy:
       matrix:
-        os: [ubuntu-24.04, macos-14, macos-15]
+        os: [ubuntu-24.04, macos-14, macos-15, macos-26]
     runs-on: ${{ matrix.os }}
     steps:
       - name: Set up Homebrew