ci: add non-blocking Codecov coverage upload job

.github/workflows/linux.yml

@@ -85,6 +85,43 @@ jobs:
           cargo test -p geozero --all-features -- --ignored postgis --test-threads 1
         env:
           DATABASE_URL: "${{ steps.pg.outputs.connection-uri }}?sslmode=disable"
+
+  coverage:
+    name: coverage - stable - x86_64-unknown-linux-gnu
+    runs-on: ubuntu-latest
+    continue-on-error: true
+    permissions:
+      contents: read
+    steps:
+      - name: Checkout
+        uses: actions/checkout@f43a0e5ff2bd294095638e18286ca9a3d1956744 # v3.6.0
+
+      - name: Install dependencies
+        shell: bash
+        run: |
+          rustc --version
+          cargo --version
+          sudo apt-get update
+          sudo apt-get install -y libgdal-dev libgeos-dev
+
+      - name: Install protoc
+        uses: arduino/setup-protoc@149f6c87b92550901b26acd1632e11c3662e381f # v1.3.0
+
+      - name: Install cargo-llvm-cov
+        shell: bash
+        run: cargo install cargo-llvm-cov --locked
+
+      - name: Generate coverage report
+        shell: bash
+        run: |
+          mkdir -p target/llvm-cov
+          cargo llvm-cov --workspace --all-targets --all-features --include-build-script --codecov --output-path target/llvm-cov/codecov.info
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v5
+        with:
+          files: target/llvm-cov/codecov.info
+          fail_ci_if_error: false
 
   # This final step is needed to mark the whole workflow as successful
   # Don't change its name - it is used by the merge protection rules