actions: html5-samples job should have a Haxe version matrix

.github/workflows/main.yml

@@ -757,13 +757,16 @@ jobs:
 
   html5-samples:
     runs-on: ubuntu-20.04
+    strategy:
+      matrix:
+        haxe-version: [3.4.7, 4.0.5, 4.1.5, 4.2.5, 4.3.6]
     steps:
 
       - uses: actions/checkout@v4
 
       - uses: krdlab/setup-haxe@v1
         with:
-          haxe-version: ${{ env.HAXE_VERSION }}
+          haxe-version: ${{ matrix.haxe-version }}
 
       - name: Set HAXEPATH
         run: |