target CI to macOS 15

Author: donnywals

.github/workflows/transloaditkit-ci.yml

@@ -5,7 +5,7 @@ jobs:
     name: Swift ${{ matrix.swift }} on ${{ matrix.os }}
     strategy:
       matrix:
-        os: ["macos-latest"]
+        os: ["macOS-15"]
         swift: ["6.0"]
     runs-on: ${{ matrix.os }}
     steps: