add workflow for testing beta toolchain

.github/workflows/beta-test.yml

@@ -0,0 +1,42 @@
+on:
+  pull_request:
+  # push:
+    # branches:
+    #   - main
+
+name: Test on Beta Toolchain
+
+env:
+  NUSHELL_CARGO_PROFILE: ci
+  NU_LOG_LEVEL: DEBUG
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref && github.ref || github.run_id }}
+  cancel-in-progress: true
+
+jobs:
+  build-and-test:
+    strategy:
+      fail-fast: true
+      matrix:
+        platform: [windows-latest, macos-latest, ubuntu-22.04]
+
+    runs-on: ${{ matrix.platform }}
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - run: rustup update beta && rustup default beta
+
+      - name: Tests
+        run: cargo test --workspace --profile ci --exclude nu_plugin_*
+      - name: Check for clean repo
+        shell: bash
+        run: |
+          if [ -n "$(git status --porcelain)" ]; then
+            echo "there are changes";
+            git status --porcelain
+            exit 1
+          else
+            echo "no changes in working directory";
+          fi