add gitea actions

.gitea/workflows/test.yaml

@@ -0,0 +1,19 @@
+name: Verilator Unit Tests
+on: [push]
+
+defaults:
+  run:
+    shell: nix develop --command bash {0}
+jobs:
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: DeterminateSystems/nix-installer-action@main
+      - run: |
+          cmake -B build/
+          cmake --build build/
+        working-directory: ./sim
+      - run: ./build/sim
+        working-directory: ./sim