adding unit test workflow

.github/workflows/dotnet.yml

@@ -5,6 +5,8 @@ on:
     branches: [ master]
   pull_request:
     branches: [ master ]
+  release:
+    branches: [ master ]
 
 jobs:
   build:

.github/workflows/unittests.yml

@@ -0,0 +1,17 @@
+name: Unit Tests
+
+on: [push, pull_request, release]
+
+jobs:
+  test:
+
+    runs-on: [ubuntu-latest]
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Setup .NET
+        uses: actions/setup-dotnet@v1
+        with:
+          dotnet-version: 5.0.x
+      - name: Run Unit Tests
+        run: dotnet test

README.md

@@ -1,5 +1,5 @@
 # Terbilang Standard
-
+[![.NET](https://github.com/DenganID/DenganID.Terbilang.Standard/actions/workflows/dotnet.yml/badge.svg)](https://github.com/DenganID/DenganID.Terbilang.Standard/actions/workflows/dotnet.yml)
 ## Synopsis
 Terbilang (netstandard2.0) is C# library for converting numeric into words in Bahasa.