Update CI job to not use mymindstorm/setup-emsdk

Author: rekhoff

.github/workflows/ci.yml

@@ -883,16 +883,22 @@ jobs:
         uses: actions/setup-dotnet@v3
         with:
           global-json-file: global.json
-
-      - name: Setup Emscripten
-        uses: mymindstorm/setup-emsdk@v14
-        with:
-          version: 4.0.23
+          
+      - name: Install emscripten (Windows)
+        shell: pwsh
+        run: |
+          git clone https://github.com/emscripten-core/emsdk.git $env:USERPROFILE\emsdk
+          cd $env:USERPROFILE\emsdk
+          .\emsdk install 4.0.21
+          .\emsdk activate 4.0.21
 
       - name: Smoketest C# AOT build (NativeAOT-LLVM)
         shell: pwsh
         run: |
           $env:EXPERIMENTAL_WASM_AOT = "1"
+          if (Test-Path "$env:USERPROFILE\emsdk\emsdk_env.ps1") {
+            & "$env:USERPROFILE\emsdk\emsdk_env.ps1" | Out-Null
+          }
           dotnet publish -c Release modules/sdk-test-cs
           if (-not (Test-Path "modules/sdk-test-cs/bin/Release/net8.0/wasi-wasm/publish/StdbModule.wasm")) {
             Write-Error "StdbModule.wasm not found"