ci: create a docker image with browsercore deps

.github/workflows/build-deps.yml

@@ -0,0 +1,60 @@
+name: build-deps
+
+on:
+  push:
+    branches:
+      - "master"
+    paths:
+      - 'vendor/lexbor-src/**'
+      - 'vendor/netsurf/**'
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+env:
+  REGISTRY: ghcr.io
+  IMAGE_NAME: browsercore/browsercore-deps
+  ZIG_VERSION: 0.11.0
+
+jobs:
+  build-deps:
+    strategy:
+      matrix:
+        include:
+          - os: linux
+            build_arch: amd64
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+          token: ${{ secrets.GH_CI_PAT }}
+          submodules: true
+
+      - name: Docker connect
+        uses: docker/login-action@65b78e6e13532edd9afa3aa52ac7964289d1a9c1
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Extract metadata (tags, labels) for Docker
+        id: meta
+        uses: docker/metadata-action@9ec57ed1fcdbf14dcef7dfbe97b2010124a938b7
+        with:
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+
+      - name: Docker build
+        uses: docker/build-push-action@f2a1d5e99d037542a71f64918e516c093c6f3fc4
+        with:
+          context: .
+          file: Dockerfile.deps
+          push: true
+          tags: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:latest
+          labels: ${{ steps.meta.outputs.labels }}
+          build-args: |
+            ZIG_VERSION=${{ env.ZIG_VERSION }}
+          platforms: ${{matrix.os}}/${{matrix.build_arch}}