CI: update to macos-15

Author: ForNeVeR

.github/workflows/main.yml

@@ -37,7 +37,7 @@ jobs:
     strategy:
       matrix:
         image:
-        - macos-14
+        - macos-15
         - ubuntu-24.04
         - ubuntu-24.04-arm
         - windows-11-arm

scripts/github-actions.fsx

@@ -74,7 +74,7 @@ let workflows = [
         dotNetJob "check" [
             strategy(failFast = false, matrix = [
                 "image", [
-                    "macos-14"
+                    "macos-15"
                     "ubuntu-24.04"
                     "ubuntu-24.04-arm"
                     "windows-11-arm"