ci: simple merge workflow

Provides all the basic functionality for a simple merging workflow: build, unit test, clippy and so
on.

.github/workflows/merge.yml

@@ -0,0 +1,111 @@
+name: merge
+
+on: pull_request
+
+env:
+  RUST_BACKTRACE: 1
+  RUSTFLAGS: "-D warnings"
+
+jobs:
+  build:
+    name: build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions-rs/toolchain@v1
+        id: toolchain
+        with:
+          profile: minimal
+          toolchain: stable
+          override: true
+      - shell: bash
+        run: cargo build --all-targets --all-features
+  checks:
+    name: various checks
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          override: true
+          components: rustfmt, clippy
+
+      - name: Cargo cache registry, index and build
+        uses: actions/[email protected]
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-cargo-cache-${{ hashFiles('**/Cargo.lock') }}-${{ hashFiles('**/Cargo.toml') }}
+
+      - name: check formatting
+        run: cargo fmt --all -- --check
+
+      - name: clippy checks
+        run: cargo clippy --all-targets --all-features -- -Dwarnings
+
+  cargo-udeps:
+    name: unused dependency check
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: nightly
+          override: true
+
+      - name: Run cargo-udeps
+        uses: aig787/cargo-udeps-action@v1
+        with:
+          version: 'latest'
+          args: '--all-targets'
+
+  cargo-deny:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - shell: bash
+      run: wget https://raw.githubusercontent.com/maidsafe/QA/master/misc-scripts/deny.toml
+    - uses: EmbarkStudios/cargo-deny-action@v1
+
+  unit-test:
+    name: unit test
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          override: true
+
+      - name: cargo cache registry, index and build
+        uses: actions/[email protected]
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-cargo-cache-${{ hashFiles('**/Cargo.lock') }}
+
+      - uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: --release
+
+  test-publish:
+    name: test publish
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          override: true
+
+      - name: dry run publish
+        run: cargo publish --dry-run