ci: install Linux image build dependencies

.gitea/workflows/ci.yml

@@ -63,6 +63,13 @@ jobs:
             raise SystemExit("migrations must use CRLF: " + ", ".join(invalid))
           PY
 
+      - name: Install native build dependencies
+        run: |
+          apt-get update
+          DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
+            cmake libdav1d-dev nasm pkg-config
+          rm -rf /var/lib/apt/lists/*
+
       - name: Install Rust toolchain
         run: |
           set -Eeuo pipefail