[SIDE-1085] add autopublication action

Author: richseviora

.github/workflows/nuget.yml

@@ -0,0 +1,26 @@
+name: NuGet Publish
+
+on:
+  release:
+    types: [ published ]
+
+defaults:
+  run:
+    working-directory: ldk/csharp
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-dotnet@v1
+        with:
+          dotnet-version: '3.1.x'
+      - run: dotnet build OliveHelpsLDK
+      - uses: rohith/publish-nuget@v22
+        name: Publish to Nuget
+        with:
+            PROJECT_FILE_PATH: ldk/csharp/OliveHelpsLDK/OliveHelpsLDK/OliveHelpsLDK.csproj
+            TAG_COMMIT: false
+            NUGET_KEY: ${{ secrets.NUGET_API_KEY }}
+            INCLUDE_SYMBOLS: true