actions-rs configuration

Uses GitHub Actions for CI, based on the `actions-rs` template:

<https://github.com/actions-rs/meta/blob/master/recipes/quickstart.md>

Configured to run tests on Linux (Ubuntu), macOS, and Windows, all of
which we should theoretically be able to support via appropriately
portable PC/SC Rust crates.

.github/workflows/rust.yml

@@ -0,0 +1,122 @@
+# Based on https://github.com/actions-rs/meta/blob/master/recipes/quickstart.md
+
+on:
+  pull_request: {}
+  push:
+    branches: master
+
+name: Rust
+
+jobs:
+  check:
+    name: Check
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v1
+
+      - name: Install stable toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          override: true
+
+      - name: Run cargo check
+        uses: actions-rs/cargo@v1
+        with:
+          command: check
+
+  test:
+    name: Test Suite
+    strategy:
+      matrix:
+        platform:
+          - ubuntu-latest
+          - macos-latest
+          # TODO: support Windows after eliminating C legacy
+          # - windows-latest
+        toolchain:
+          - 1.39.0
+          - stable
+    runs-on: ${{ matrix.platform }}
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v1
+
+      - name: Install stable toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: ${{ matrix.toolchain }}
+          override: true
+
+      - name: Run cargo test
+        uses: actions-rs/cargo@v1
+        with:
+          command: test
+
+  fmt:
+    name: Rustfmt
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v1
+
+      - name: Install stable toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          override: true
+
+      - name: Install rustfmt
+        run: rustup component add rustfmt
+
+      - name: Run cargo fmt
+        uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check
+
+  clippy:
+    name: Clippy
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v1
+
+      - name: Install stable toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          override: true
+
+      - name: Install clippy
+        run: rustup component add clippy
+
+      - name: Run cargo clippy
+        uses: actions-rs/cargo@v1
+        with:
+          command: clippy
+          args: -- -D warnings
+
+  # TODO: use actions-rs/audit-check
+  security_audit:
+    name: Security Audit
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v1
+
+      - name: Install stable toolchain
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          override: true
+
+      - name: Install cargo audit
+        run: cargo install cargo-audit
+
+      - name: Run cargo audit
+        uses: actions-rs/cargo@v1
+        with:
+          command: audit
+          args: --deny-warnings

README.md

@@ -55,7 +55,7 @@ USE AT YOUR OWN RISK!
 
 ## Requirements
 
-- Rust 1.36+
+- Rust 1.39+
 
 ## Code of Conduct
 
@@ -111,7 +111,7 @@ or conditions.
 [docs-image]: https://docs.rs/yubikey-piv/badge.svg
 [docs-link]: https://docs.rs/yubikey-piv/
 [license-image]: https://img.shields.io/badge/license-BSD-blue.svg
-[rustc-image]: https://img.shields.io/badge/rustc-1.36+-blue.svg
+[rustc-image]: https://img.shields.io/badge/rustc-1.39+-blue.svg
 [maintenance-image]: https://img.shields.io/badge/maintenance-experimental-blue.svg
 [build-image]: https://github.com/tarcieri/yubikey-piv.rs/workflows/Rust/badge.svg
 [build-link]: https://github.com/tarcieri/yubikey-piv.rs/actions