Create workflows for unit testing

.github/workflows/opensk_build.yml

@@ -0,0 +1,30 @@
+---
+name: OpenSK build
+on:
+  push:
+  pull_request:
+    types: [opened, synchronize, reopened]
+
+jobs:
+  build:
+    runs-on: ubuntu-18.04
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: nightly
+          target: thumbv7em-none-eabi
+          override: true
+      - uses: actions/setup-python@v1
+        with:
+          python-version: 3.7
+      - name: Install Python dependencies
+        run: python -m pip install --upgrade pip setuptools wheel
+      - name: Set up OpenSK
+        run: ./setup.sh
+
+      - name: Building OpenSK
+        uses: actions-rs/cargo@v1
+        with:
+          command: build
+          args: --release --target=thumbv7em-none-eabi --features with_ctap1