Check code for clippy lints and formatting with CI

.github/workflows/lint.yml

@@ -0,0 +1,58 @@
+# Copied from Twilight's Lint workflow.
+#
+# https://github.com/twilight-rs/twilight/blob/trunk/.github/workflows/lint.yml
+name: Lint
+
+on: [push, pull_request]
+
+jobs:
+  clippy:
+    name: Clippy
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v2
+
+      - name: Install stable toolchain
+        id: toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: nightly
+          components: clippy
+          profile: minimal
+          override: true
+
+      - name: Setup cache
+        uses: actions/cache@v2
+        with:
+          path: |
+            ~/.cargo/registry
+            ~/.cargo/git
+            target
+          key: ${{ runner.os }}-clippy-rustc-${{ steps.toolchain.outputs.rustc_hash }}-${{ hashFiles('**/Cargo.lock') }}
+
+      - name: Run clippy
+        uses: actions-rs/clippy-check@v1
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          args: --workspace --tests
+
+  rustfmt:
+    name: Format
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v2
+
+      - name: Install stable toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: nightly
+          components: rustfmt
+          profile: minimal
+          override: true
+
+      - name: Run cargo fmt
+        run: cargo fmt --all -- --check