Use a vckpg binary cache on Windows

Author: vector-of-bool

.github/workflows/ci.yml

@@ -97,11 +97,17 @@ jobs:
   build-windows:
     name: Build & Test (Windows, VS 2022)
     strategy:
+      fail-fast: false
       matrix:
         arch: [x86, amd64, arm64]
     runs-on: windows-2022
     steps:
       - *checkout
+      - name: Prepare Caches
+        uses: actions/cache@v4
+        with:
+          path: _build/_cache
+          key: msvc-${{matrix.arch}}
       - name: Build & Test
         shell: pwsh
         # 17.* select VS 2022

tools/ci.ps1

@@ -27,6 +27,11 @@ $this_dir = $PSScriptRoot
 
 $root = Split-Path -Parent $this_dir
 
+# Set the directory where vcpkg will store its binary cache artifacts. This can
+# be persisted between CI runs
+$env:VCPKG_DEFAULT_BINARY_CACHE = "$root/_build/_cache/vcpkg"
+[void](New-Item -ItemType Directory $env:VCPKG_DEFAULT_BINARY_CACHE -Force)
+
 Write-Verbose "Loading uv environment..."
 $uv_env = Get-UvEnvironment -ArgumentList "--group=build"
 Write-Verbose "Loading MSVS environment..."