ci: disable codecov patch (#629)

I don't really need the patch feature right now, so let's disable it.

.github/workflows/coverage.yml

@@ -0,0 +1,48 @@
+# Code coverage generation via cargo-tarpaulin, and uploaded to codecov.
+
+name: codecov
+
+on:
+  workflow_dispatch:
+  pull_request:
+  push:
+    branches:
+      - master
+
+jobs:
+  pre_job:
+    runs-on: ubuntu-latest
+    outputs:
+      should_skip: ${{ steps.skip_check.outputs.should_skip }}
+    steps:
+      - id: skip_check
+        uses: fkirc/skip-duplicate-actions@master
+        with:
+          concurrent_skipping: "same_content_newer"
+          skip_after_successful_duplicate: "true"
+          paths: '["tests/**", "src/**", ".github/workflows/codecov.yml", ".cargo/**", "Cargo.toml", "Cargo.lock", "build.rs"]'
+          do_not_skip: '["workflow_dispatch"]'
+
+  coverage:
+    needs: pre_job
+    if: ${{ needs.pre_job.outputs.should_skip != 'true' }}
+    runs-on: ubuntu-latest
+    container:
+      image: xd009642/tarpaulin:develop
+      options: --security-opt seccomp=unconfined
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - uses: Swatinem/rust-cache@v1
+        with:
+          key: ${{ matrix.triple.target }}
+
+      - name: Generate code coverage
+        run: |
+          cargo tarpaulin --verbose --all-features --workspace --run-types AllTargets --timeout 120 --out Xml
+
+      - name: Upload to codecov.io
+        uses: codecov/codecov-action@v2
+        with:
+          fail_ci_if_error: true