github/workflows: Add workflow for renesas-ra port.

Signed-off-by: Takeo Takahashi <takeo.takahashi.xv@renesas.com>

.github/workflows/ports_renesas-ra.yml

@@ -0,0 +1,24 @@
+name: renesas-ra port
+
+on:
+  push:
+  pull_request:
+    paths:
+      - '.github/workflows/*.yml'
+      - 'tools/**'
+      - 'py/**'
+      - 'extmod/**'
+      - 'lib/**'
+      - 'drivers/**'
+      - 'ports/renesas-ra/**'
+
+jobs:
+  build_renesas_ra_board:
+    runs-on: ubuntu-20.04
+    steps:
+    - uses: actions/checkout@v2
+    - name: Install packages
+      run: source tools/ci.sh && ci_renesas_ra_setup
+    - name: Build
+      run: source tools/ci.sh && ci_renesas_ra_board_build
+