github/workflows: Add qemu-riscv port to CI.

Signed-off-by: Alessandro Gatti <a.gatti@frob.it>

.github/workflows/ports_qemu-riscv.yml

@@ -0,0 +1,33 @@
+name: qemu-riscv port
+
+on:
+  push:
+  pull_request:
+    paths:
+      - '.github/workflows/*.yml'
+      - 'tools/**'
+      - 'py/**'
+      - 'extmod/**'
+      - 'shared/**'
+      - 'lib/**'
+      - 'drivers/**'
+      - 'ports/qemu-arm/main.c'
+      - 'ports/qemu-riscv/**'
+      - 'tests/**'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build_and_test:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: Install packages
+      run: source tools/ci.sh && ci_qemu_riscv_setup
+    - name: Build and run test suite
+      run: source tools/ci.sh && ci_qemu_riscv_build
+    - name: Print failures
+      if: failure()
+      run: grep --before-context=100 --text "FAIL" ports/qemu-riscv/build/console.out