Update Gitea on-push workflow

.gitea/workflows/on-push.yaml

@@ -5,6 +5,14 @@ jobs:
   build-and-test:
     runs-on: linux
     container: code.helloryan.se/infra/buildenv/cxx-amd64-fedora-40:latest
+    volumes:
+      - /build
     steps:
       - name: Check out repository code
         uses: actions/checkout@v4
+      - name: Initialize
+        run: bdep init -C /build cc config.cxx=g++ config.cc.coptions="-Wall -Werror"
+      - name: Build
+        run: b
+      - name: Test
+        run: b test