Add cargo lint.

.github/workflows/lint.yml

@@ -0,0 +1,36 @@
+on:
+  push:
+    branches:
+      - '*'         # matches every branch that doesn't contain a '/'
+      - '*/*'       # matches every branch containing a single '/'
+      - '**'        # matches every branch
+      - '!master'   # excludes master
+
+jobs:
+  cargolint:
+    name: Rust lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+      - name: Set up cargo cache
+        uses: actions/cache@v3
+        continue-on-error: false
+        with:
+          path: |
+            ~/.cargo/bin/
+            ~/.cargo/registry/index/
+            ~/.cargo/registry/cache/
+            ~/.cargo/git/db/
+            target/
+          key: ${{ runner.os }}-cargo-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: ${{ runner.os }}-cargo-
+      - name: Add required index.html
+        run: |
+          touch ./static/index.html
+      - uses: actions-rs/cargo@v1
+        with:
+          command: clippy
+