Create CI workflow

.github/workflows/build.yml

@@ -0,0 +1,34 @@
+name: Build console app
+
+on:
+  push:
+    branches: [ main ]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+
+    - uses: actions/checkout@v2
+
+    - name: Set up .NET
+      uses: actions/setup-dotnet@v1
+      with:
+        dotnet-version: 5.0.x
+
+    - name: Restore dependencies
+      run: dotnet restore
+
+    - name: Build
+      run: dotnet build --no-restore --configuration Release
+
+    - name: Publish
+      run: dotnet publish -c Release -r win-x86 -p:PublishSingleFile=true --self-contained false
+
+    - name: Upload a Build Artifact
+      uses: actions/upload-artifact@v2.2.4
+      with:
+        name: SymLinkMirror
+        path: bin/Release/net5.0/win-x86/publish/SymLinkMirror.exe