build: add github ci

.github/workflows/build.yml

@@ -0,0 +1,56 @@
+on: [push, pull_request]
+
+name: Build
+
+jobs:
+  build:
+    name: Build
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os:
+          - ubuntu-latest
+          - macOS-latest
+          - windows-latest
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          target: ${{ matrix.target }}
+          override: true
+
+      - uses: actions-rs/cargo@v1
+        with:
+          use-cross: true
+          command: test
+
+      - uses: actions-rs/cargo@v1
+        with:
+          use-cross: true
+          command: build
+          args: --release
+
+  cross_compile:
+    name: Cross compile
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        target:
+          - armv7-unknown-linux-gnueabihf
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          target: ${{ matrix.target }}
+          override: true
+      - uses: actions-rs/cargo@v1
+        with:
+          use-cross: true
+          command: build
+          args: --release --target=${{ matrix.target }}
+
+