Add Redox OS CI (#394)

Author: Copilot

.github/workflows/redox.yml

@@ -0,0 +1,25 @@
+name: Redox CI
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+
+permissions: {}
+
+jobs:
+  redox:
+    runs-on: ubuntu-latest
+    container: redoxos/redoxer
+    steps:
+      - name: Install Toolchain
+        run: |
+          ln -sT /root/.redoxer ~/.redoxer
+      - uses: actions/checkout@v6
+      - name: Build
+        run: redoxer build
+      - name: Test
+        run: redoxer test --tests # doc tests aren't supported