meta: set up CI (#21)

* meta: set up CI

Fixes: https://github.com/zkat/miette/issues/2

.github/workflows/ci.yml

@@ -0,0 +1,47 @@
+name: CI
+
+on: [push, pull_request]
+
+env:
+  RUSTFLAGS: -Dwarnings
+
+jobs:
+  fmt_and_docs:
+    name: Check fmt & build docs
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: stable
+          components: rustfmt
+          override: true
+      - name: rustfmt
+        run: cargo fmt --all -- --check
+      - name: docs
+        run: cargo doc --no-deps
+
+  build_and_test:
+    name: Build & Test
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        rust: [1.54.0, stable]
+        os: [ubuntu-latest, macOS-latest, windows-latest]
+
+    steps:
+      - uses: actions/checkout@v1
+      - name: Install Rust
+        uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: ${{ matrix.rust }}
+          components: clippy
+          override: true
+      - name: Clippy
+        run: cargo clippy --all -- -D warnings
+      - name: Run tests
+        run: cargo test --all --verbose
+