pipe pip installation to stdout

Author: pashagolub

src/install.ps1

@@ -1,6 +1,7 @@
 Write-Host "--- Installing Python runtime ---" -ForegroundColor blue
 Start-Process -FilePath .\python-install.exe -ArgumentList "/quiet InstallAllUsers=1 PrependPath=1 Include_test=0 Include_launcher=0" -NoNewWindow -Wait
-python.exe -m pip install --upgrade pip
+# update pip and pipe output to stdout to avoid parallel execution
+python.exe -m pip install --upgrade pip | Out-Default
 Write-Host "--- Python runtime installed ---`n" -ForegroundColor green
 
 # Update Path variable with installed Python