SignTool password masking fails with special characters

[markgould]

The password masking implemented in #861 fails if the password contains a special character.

For example a password of 1@234567 will show in the logs as ********@234567

[shiftkey]

@markgould I'd take a PR to improve this regex to capture anything that looks like text

Squirrel.Windows/src/Update/Program.cs

Lines 621 to 623 in 47de3b6

	var optsWithPasswordHidden = new Regex(@"/p\s+\w+").Replace(signingOpts, "/p ********");
	var msg = String.Format("Failed to sign, command invoked was: '{0} sign {1} {2}'",
	exe, optsWithPasswordHidden, exePath);