ci: Add GitHub workflows for building and publishing

Add a workflow that builds, tests and runs lint checks on the crate.

Add a workflow for publishing the crate to `crates.io`
when a new git tag is pushed.

.github/workflows/publish.yml

@@ -0,0 +1,17 @@
+name: Publish crates
+
+on:
+  push:
+    tags: [ v* ]
+
+env:
+  CARGO_REGISTRY_TOKEN: ${{ secrets.CRATES_IO_TOKEN }}
+
+jobs:
+  publish-crate:
+    name: Publish to crates.io
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - name: Run cargo publish
+      run: cargo publish

.github/workflows/rust.yml

@@ -0,0 +1,35 @@
+name: Rust build checks
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+env:
+  CARGO_TERM_COLOR: always
+
+jobs:
+  build:
+    name: Build and test
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - name: Build
+      run: cargo build --verbose
+    - name: Run tests
+      run: cargo test --verbose
+  fmt:
+    name: Check code formatting
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - name: Run cargo fmt
+      run: cargo fmt -- --check
+  clippy:
+    name: Clippy lints
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - name: Run cargo clippy
+      run: cargo clippy --tests -- --deny warnings