Introduce GitHub Action based CI

This change adds a configuration file for a GitHub Actions based CI
pipeline to the repository. This file (directly or indirectly) controls
the environment in which to build and test, and is also used for some
additional linting.

.github/workflows/test.yml

@@ -0,0 +1,45 @@
+# Copyright (C) 2023 Daniel Mueller <deso@posteo.net>
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+name: Test
+
+on:
+  pull_request:
+  push:
+
+env:
+  CARGO_TERM_COLOR: always
+  RUST_BACKTRACE: 1
+  # Build without debug information enabled to decrease compilation time
+  # and binary sizes in CI. This option is assumed to only have marginal
+  # effects on the generated code, likely only in terms of section
+  # arrangement. See
+  # https://doc.rust-lang.org/cargo/reference/environment-variables.html
+  # https://doc.rust-lang.org/rustc/codegen-options/index.html#debuginfo
+  RUSTFLAGS: '-C debuginfo=0'
+
+jobs:
+  test:
+    name: Build and test [${{ matrix.profile }}]
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        rust: [stable]
+        profile: [dev, release]
+    steps:
+    - uses: actions/checkout@v3
+    - uses: dtolnay/rust-toolchain@master
+      with:
+        toolchain: ${{ matrix.rust }}
+    - name: Build & test ${{ matrix.profile }}
+      run: |
+        cargo build --profile=${{ matrix.profile }} --all-targets
+        cargo test --profile=${{ matrix.profile }}
+  clippy:
+    name: Lint with clippy
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: dtolnay/rust-toolchain@stable
+      - run: cargo clippy --no-deps --all-targets --all-features --tests -- -A unknown_lints -A deprecated -D warnings