added a github actions build file

.github/workflows/build.yml

@@ -0,0 +1,36 @@
+name: flash loader template
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+env:
+  # Customize the CMake build type here (Release, Debug, RelWithDebInfo, etc.)
+  BUILD_TYPE: Release
+
+jobs:
+  build:
+    # The CMake configure and build commands are platform agnostic and should work equally well on Windows or Mac.
+    # You can convert this to a matrix build if you need cross-platform coverage.
+    # See: https://docs.github.com/en/free-pro-team@latest/actions/learn-github-actions/managing-complex-workflows#using-a-build-matrix
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: arm-none-eabi-gcc install
+        uses: carlosperate/arm-none-eabi-gcc-action@v1.3.0
+
+      - name: arm-none-eabi-gcc version
+        run: arm-none-eabi-gcc --version
+
+      - name: Configure CMake
+        # Configure CMake in a 'build' subdirectory. `CMAKE_BUILD_TYPE` is only required if you are using a single-configuration generator such as make.
+        # See https://cmake.org/cmake/help/latest/variable/CMAKE_BUILD_TYPE.html?highlight=cmake_build_type
+        run: CC=arm-none-eabi-gcc CXX=arm-none-eabi-g++ cmake -B ${{github.workspace}}/build
+
+      - name: Build
+        # Build your program with the given configuration
+        run: cmake --build ${{github.workspace}}/build --config ${{env.BUILD_TYPE}}