Use Nerdbank.GitVersioning

Version the VSIX file and assemblies.

Directory.Build.Props

@@ -5,4 +5,10 @@
     <Copyright>Copyright © GitHub, Inc. 2014-2018</Copyright>
     <LangVersion>7.3</LangVersion>
   </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include="Nerdbank.GitVersioning">
+      <Version>3.0.26</Version>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+  </ItemGroup>
 </Project>

src/GitHub.VisualStudio.Vsix/source.extension.vsixmanifest

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
 <PackageManifest Version="2.0.0" xmlns="http://schemas.microsoft.com/developer/vsx-schema/2011" xmlns:d="http://schemas.microsoft.com/developer/vsx-schema-design/2011">
   <Metadata>
-    <Identity Id="c3d3dc68-c977-411f-b3e8-03b0dccf7dfc" Version="2.10.8.0" Language="en-US" Publisher="GitHub, Inc" />
+    <Identity Id="c3d3dc68-c977-411f-b3e8-03b0dccf7dfc" Version="|%CurrentProject%;GetBuildVersion|" Language="en-US" Publisher="GitHub, Inc" />
     <DisplayName>GitHub Extension for Visual Studio</DisplayName>
     <Description xml:space="preserve">A Visual Studio Extension that brings the GitHub Flow into Visual Studio.</Description>
     <PackageId>GitHub.VisualStudio</PackageId>

version.json

@@ -0,0 +1,13 @@
+{
+  "$schema": "https://raw.githubusercontent.com/AArnott/Nerdbank.GitVersioning/master/src/NerdBank.GitVersioning/version.schema.json",
+  "version": "1.0-beta",
+  "publicReleaseRefSpec": [
+    "^refs/heads/master$",
+    "^refs/heads/v\\d+(?:\\.\\d+)?$"
+  ],
+  "cloudBuild": {
+    "buildNumber": {
+      "enabled": true
+    }
+  }
+}