removes deprecated set-env from build script

.github/workflows/docker.yml

@@ -42,7 +42,7 @@ jobs:
         run: |
           if("$($Env:GITHUB_REF)".contains("$($Env:RELEASE_BRANCH)")) {
             Write-Host "Setting build type to Release"
-            Write-Output "::set-env name=BUILD_TYPE::Release"
+            Write-Output "echo "BUILD_TYPE='Release'" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append"
           }
       # Fetch all tags
       - name: Fetch tags
@@ -52,7 +52,7 @@ jobs:
         shell: powershell
         run: |
           $version = ./.github/scripts/GenerateVersionNumber.ps1
-          Write-Output "::set-env name=VERSION::$version"
+          Write-Output "echo "VERSION=$version" | Out-File -FilePath $env:GITHUB_ENV -Encoding utf8 -Append"
       # Use the version number to set the version of the assemblies
       - name: Update AssemblyInfo.cs
         shell: powershell