Update appveyor.yml

Author: RyuzakiH

appveyor.yml

@@ -1,8 +1,8 @@
-version: 2.0.0
+version: 2.0.{build}
 image: Visual Studio 2017
 before_build:
  - dotnet restore
 build_script:
  - dotnet build /verbosity:quiet "TempMail-API.sln"
 test_script:
- - dotnet test --no-build .\test\TempMail.Tests\TempMail.Tests.csproj
+ - dotnet test --no-build .\test\TempMail.Tests\TempMail.Tests.csproj