[ci] Pin Windows runner to Windows 2025 (#566)

Rather than using Windows-latest this PR updates the ci to use a pinned
version of Windows (set to the latest version available). This is so if
you happen to have an issue with the Windows build you know exactly
which version of Windows it is running, rather than having to dig into
the ci, or Github runner documentation.

.github/workflows/main.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-22.04, macos-latest, windows-latest]
+        os: [ubuntu-22.04, macos-latest, windows-2025]
         clang_version: [10.0.0]
         # use different LLVM versions among oses because of the lack of
         # official assets on github.
@@ -18,7 +18,7 @@ jobs:
           - os: macos-latest
             clang_version: 10.0.0
             llvm_asset_suffix: x86_64-apple-darwin
-          - os: windows-latest
+          - os: windows-2025
             clang_version: 10.0.0
           - os: ubuntu-22.04
             clang_version: 16.0.0
@@ -27,7 +27,7 @@ jobs:
           - os: macos-latest
             clang_version: 15.0.7
             llvm_asset_suffix: x86_64-apple-darwin21.0
-          - os: windows-latest
+          - os: windows-2025
             clang_version: 16.0.0
             enable_pic: true
     steps:
@@ -51,7 +51,7 @@ jobs:
         echo "CC=$(pwd)/llvm/bin/clang.exe" >> $GITHUB_ENV
         echo "AR=$(pwd)/llvm/bin/llvm-ar.exe" >> $GITHUB_ENV
         echo "NM=$(pwd)/llvm/bin/llvm-nm.exe" >> $GITHUB_ENV
-      if: matrix.os == 'windows-latest'
+      if: matrix.os == 'windows-2025'
 
     - name: Override llvm-nm with one from rustup (Windows)
       run: |
@@ -59,7 +59,7 @@ jobs:
         rustup default stable
         rustup component add llvm-tools-preview
         echo "NM=$(rustc --print sysroot|sed 's|C:|/c|'|sed 's|\\|/|g')/lib/rustlib/x86_64-pc-windows-msvc/bin/llvm-nm.exe" >> $GITHUB_ENV
-      if: matrix.os == 'windows-latest'
+      if: matrix.os == 'windows-2025'
 
     - name: Install LLVM tools (MacOS)
       shell: bash
@@ -156,7 +156,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
+        os: [ubuntu-latest, macos-latest, windows-2025]
     steps:
     - uses: actions/checkout@v4.1.7
       with: