build.yml: use macOS-15 (was macOS-14)

Author: msgilligan

.github/workflows/build.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-24.04, ubuntu-24.04-arm, macOS-14]
+        os: [ubuntu-24.04, ubuntu-24.04-arm, macOS-15]
         distribution: ['temurin']
       fail-fast: false
     name: ${{ matrix.os }} JDK 25 (via Gradle Java toolchains)
@@ -57,7 +57,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-24.04, ubuntu-24.04-arm, macOS-14]
+        os: [ubuntu-24.04, ubuntu-24.04-arm, macOS-15]
         java: [ '25' ]
         distribution: [ 'graalvm' ]
       fail-fast: false
@@ -120,7 +120,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-24.04, ubuntu-24.04-arm, macOS-14]
+        os: [ubuntu-24.04, ubuntu-24.04-arm, macOS-15]
       fail-fast: false
     name: ${{ matrix.os }} Nix
     steps: