try github actions

.github/workflows/ci.yml

@@ -0,0 +1,25 @@
+name: Continuous Integration
+on:
+  push:
+    branches:
+      - staging
+      - trying
+      - master
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v1
+    - name: Install toolchain
+      run: rustup toolchain install nightly
+    - name: Use toolchain
+      run: rustup override add nightly
+    - name: Install target
+      run: rustup target add thumbv7em-none-eabihf
+    - name: Build release
+      run: cargo build --verbose --release
+    - name: Build semihosting
+      run: cargo build --verbose --features semihosting
+    - name: Build bkpt
+      run: cargo build --verbose --features bkpt,semihosting