Pipeline | dotnet build $PROJECT_PATH with spaces in the path

[alex75]

This is my pipeline:

image: microsoft/dotnet:sdkimage: mcr.microsoft.com/dotnet/core/sdk:3.1-buster
pipelines:
  default:
    - step: 
        caches:
          - dotnetcore       
         script: 
           - export PROJECT_NAME="Web Site/My Website.sln"   
           - dotnet restore "Web Site"   
       
           #- dotnet build $PROJECT_NAME          # <-- this does not work

           - dotnet build "Web Site/My Website.sln"  # <-- this works!
 

The path of the VS solution file is this: Web Site/My WEbsite.sln 
Essentially I'm not able to wrap the path in double quote using a (bash) variable,
to obtain the result of the last line.

I tried:
- export PROJECT_NAME="\"Web Site/My Website.sln\""
- export PROJECT_NAME="'Web Site/My Website.sln'"
- dotnet build "$PROJECT_NAME" 

They all fails like there is no quote surrounding the path.