Version constraint on .NET (#21)

Enforces version constraint on .NET so that runners don't use too new a version of .NET (macos arm64 runners will at the moment).
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Co-authored-by: Siva Somayyajula <somayyas@amazon.com>

Author: Siva Somayyajula

action.yml

@@ -9,5 +9,15 @@ inputs:
     required: true
     default: "3.1.0"
 runs:
-  using: "node16"
-  main: "dist/index.js"
+  using: "composite"
+  steps:
+  - uses: actions/setup-dotnet@v4
+    with:
+      dotnet-version: '6.0.x'
+  - uses: actions/setup-node@v4
+    with:
+      node-version: 16
+  - run: node dist/index.js
+    shell: bash
+    env:
+      INPUT_DAFNY-VERSION: ${{ inputs.dafny-version }}