with https://github.com/guitarrapc/GitContinuousPull

GitCredentialAutomation.ps1

# install valentia
powershell -NoProfile -ExecutionPolicy unrestricted -Command 'iex ([Text.Encoding]::UTF8.GetString([Convert]::FromBase64String((irm "https://api.github.com/repos/guitarrapc/valentia/contents/valentia/Tools/RemoteInstall.ps1").Content))).Remove(0,1)'

# install GitContinuousPull
powershell -NoProfile -ExecutionPolicy unrestricted -Command 'iex ([Text.Encoding]::UTF8.GetString([Convert]::FromBase64String((irm "https://api.github.com/repos/guitarrapc/GitContinuousPull/contents/GitContinuousPull/Tools/RemoteInstall.ps1").Content))).Remove(0,1)'

# set git-credential-wincred into .girhub. Now git.exe read github credential from Windows Credential Manager.
git config --global credential.helper wincred

# set your github authenticated user/password
Set-ValentiaCredential -TargetName git

# then input some repository. git credential will automatically insert into Windows Credential Manager as git-credential-windred needed.
Import-Module GitContinuousPull -Force -Verbose
$param = @(
    @{
        RepositoryUrl = "https://github.com/neuecc/RespClient.git"
        GitPath = "C:\Repository"
        LogFolderPath = "C:\logs\RespClient"
        LogName = "$((Get-Date).ToString("yyyyMMdd-HHmmss")).log"
    }
)

$param | %{Start-GitContinuousPull @_ -Verbose}

# now both git and submodule never ask you for a credential anymore.