Run nightly tests with new xmake versions.

.github/workflows/test-new-xmake-nightly.yml

@@ -0,0 +1,38 @@
+name: CHERIoT RTOS Tests
+
+on:
+  schedule:
+    - cron: '0 0 * * *'
+  workflow_dispatch:
+
+jobs:
+  run-tests:
+    strategy:
+      fail-fast: false
+    runs-on: ubuntu-latest
+    container:
+      image: ghcr.io/cheriot-platform/devcontainer:latest
+      options: --user 1001
+    steps:
+    - name: Checkout repository and submodules
+      uses: actions/checkout@v3
+      with:
+        submodules: recursive
+    - name: Build latest xmake
+      run: |
+        # Make sure that we don't accidentally use the installed version
+        sudo apt remove -y  xmake
+        curl -fsSL https://xmake.io/shget.text | bash -s dev
+    - name: Build tests
+      run: |
+        source ~/.xmake/profile
+        xmake --version
+        cd tests
+        xmake f --board=${{ matrix.board }} --sdk=/cheriot-tools/ ${{ matrix.build-flags }}
+        xmake
+    - name: Run tests
+      run: |
+        source ~/.xmake/profile
+        xmake --version
+        cd tests
+        xmake run