Add macos-15 and macos-26 runners, remove macos-12 (no longer available), macos-13 (fails brew install octave).

Author: rdzman

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [macos-12, macos-13, macos-latest]
+        os: [macos-14, macos-15, macos-26, macos-latest]
 
     runs-on: ${{ matrix.os }}