Replace macos-latest with the specific macos-15 (#7718)

Prefer explicit updates of runner version.
No change in the actual macos runner used at this time.

Follow up to #7716 and #7709

Author: pavoljuhas

.github/workflows/ci-daily.yml

@@ -74,7 +74,7 @@ jobs:
     strategy:
       matrix:
         python-version: ['3.11', '3.12', '3.13']
-    runs-on: macos-latest
+    runs-on: macos-15
     steps:
       - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
       - uses: actions/setup-python@e797f83bcb11b83ae66e0230d6156d7c80228e7c # v6.0.0

.github/workflows/ci.yml

@@ -319,7 +319,7 @@ jobs:
     strategy:
       matrix:
         python-version: ['3.11', '3.12', '3.13']
-    runs-on: macos-latest
+    runs-on: macos-15
     steps:
       - name: Check out source repository
         uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0