chore: add GitHub Actions pipeline (#15)

Author: hazzik

.github/workflows/pack.yml

@@ -0,0 +1,32 @@
+name: .NET
+
+on:
+  push:
+    branches: [ "master" ]
+    tags: [ "*" ]
+  pull_request:
+    branches: [ "master" ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v3
+      with:
+        fetch-depth: 0 # avoid shallow clone
+
+    - name: Setup .NET
+      uses: actions/setup-dotnet@v3
+      with:
+        dotnet-version: 8.0.x
+
+    - name: Pack
+      run: dotnet pack -c Release -o out -p:ContinuousIntegrationBuild=true
+
+    - name: Push
+      run: dotnet nuget push *.nupkg -s nuget.org -k $NUGET_API_KEY
+      if: startsWith(github.ref, 'refs/tags/') || github.ref == 'refs/heads/master'
+      working-directory: out
+      env:
+        NUGET_API_KEY: ${{ secrets.NUGET_API_KEY }}