Only run test compile on appveyor

Author: wallymathieu

appveyor.yml

@@ -17,7 +17,7 @@ install:
   - cmd: git submodule update --init --recursive
 build_script:
   - cmd: dotnet restore ./FSharpPlus.sln
-  - cmd: dotnet build -c Release ./FSharpPlus.sln
+  #- cmd: dotnet build -c Release ./FSharpPlus.sln
   - cmd: dotnet test -c Test tests/FSharpPlus.Tests
   - ps: if ($env:VersionSuffix) { dotnet pack build.proj --version-suffix $env:VersionSuffix } else { dotnet pack build.proj }
 test: off