Update yarn version in CI, resolve dependency conflict

build/install-yarn.ps1

@@ -0,0 +1,12 @@
+# via https://gist.github.com/FeodorFitsner/1056703ec92bd6a3012c15fe78a5e162
+
+Write-Host "Installing Yarn..." -ForegroundColor Cyan
+
+Write-Host "Downloading..."
+$msiPath = "$env:TEMP\yarn.msi"
+(New-Object Net.WebClient).DownloadFile('https://github.com/yarnpkg/yarn/releases/download/v1.17.3/yarn-1.17.3.msi', $msiPath)
+
+Write-Host "Installing..."
+cmd /c start /wait msiexec /i "$msiPath" /quiet
+
+Write-Host "Yarn installed" -ForegroundColor Green