actions: try neko tests on Windows instead of Ubuntu

Context3D unavailable error on Ubuntu

.github/workflows/main.yml

@@ -185,7 +185,8 @@ jobs:
     strategy:
       matrix:
         haxe-version: [4.0.5, 4.1.5, 4.2.5, 4.3.2]
-    runs-on: ubuntu-latest
+    # Context3D unavailable error on ubuntu
+    runs-on: windows-latest
     steps:
       - uses: actions/checkout@v3
 
@@ -195,7 +196,7 @@ jobs:
 
       - name: Set HAXEPATH
         run: |
-          echo "HAXEPATH=$HAXE_STD_PATH/.." >> $GITHUB_ENV
+          echo "HAXEPATH=$Env:HAXE_STD_PATH\.." >> $Env:GITHUB_ENV
 
       - name: Install Haxe dependencies
         run: |
@@ -206,7 +207,7 @@ jobs:
 
       - name: Setup environment
         run: |
-          haxelib dev starling $GITHUB_WORKSPACE
+          haxelib dev starling $Env:GITHUB_WORKSPACE
 
       - name: Run tests on Neko
         working-directory: tests