Add automatic PR checks

This adds automatic checks for each PR:

  * `cargo clippy`
  * `cargo fmt` (checks that `cargo fmt` is a no-op)
  * [`cargo msrv`] (verifies that minimum supported Rust version is what
    is set as `rust-version` in Cargo.toml)
  * `cargo test`

This also sets GitHub’s dependabot to check for updates to the GitHub
actions used monthly.

Currently, the crate works on any version of Rust from 1.56 on up. This
sets `rust-version` in Cargo.toml so that any change to the minimum
supported Rust version (MSRV) will be noticed.

Finally, this removes the rust-toolchain file and adds it to .gitignore.
This allows the crate to be developed on any version of Rust ≥1.56.

Fixes: cloudhead#17 — Set up continious integration

[`cargo msrv`]: https://github.com/foresterre/cargo-msrv

.github/dependabot.yml

@@ -0,0 +1,7 @@
+# https://docs.github.com/github/administering-a-repository/configuration-options-for-dependency-updates
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "monthly"

.github/workflows/pr-checks.yaml

@@ -0,0 +1,53 @@
+name: PR checks
+
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - $default-branch
+  pull_request:
+
+jobs:
+  clippy:
+    name: cargo clippy
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions-rust-lang/setup-rust-toolchain@v1
+        with:
+          components: clippy
+      - run: cargo clippy --all-features --all-targets
+
+  fmt:
+    name: cargo fmt
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions-rust-lang/setup-rust-toolchain@v1
+        with:
+          components: rustfmt
+      - uses: actions-rust-lang/rustfmt@v1
+
+  msrv:
+    name: cargo msrv
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions-rust-lang/setup-rust-toolchain@v1
+      - uses: taiki-e/install-action@v2
+        with:
+          tool: cargo-msrv
+      - run: cargo msrv verify
+
+  test:
+    name: cargo test
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions-rust-lang/setup-rust-toolchain@v1
+      - run: cargo build --tests
+      - run: cargo test

.gitignore

@@ -1,2 +1,3 @@
 /target
 Cargo.lock
+/rust-toolchain

Cargo.toml

@@ -10,6 +10,7 @@ version = "3.0.0"
 authors = ["Alexis Sellier <[email protected]>"]
 edition = "2021"
 license = "MIT"
+rust-version = "1.56"
 
 [dependencies]
 libc = "0.2.134"