Cloning repo fails on Windows because of colon in filename

[vicmortelmans]

Hi,

I run spacemacs on Windows. Cloning the repo of this package fails on Windows, because there are colons in filenames in the screenshots directory.

(Spacemacs) --> installing package: elgantt@dotfile... [1/1]
Fetcher: github
Source: legalnonsense/elgantt

Cloning https://github.com/legalnonsense/elgantt.git to d:/Users/amcaj/.emacs.d/.cache/quelpa/build/elgantt/
(Spacemacs) Error: 
An error occurred while installing elgantt (error: (error Failed to checkout ‘elgantt’: ‘Command ’(git clone https://github.com/legalnonsense/elgantt.git d:/Users/amcaj/.emacs.d/.cache/quelpa/build/elgantt/ --origin origin)’ exited with non-zero status 128: Cloning into 'd:/Users/amcaj/.emacs.d/.cache/quelpa/build/elgantt'...
error: invalid path 'screenshots/output-2020-07-19-16:21:10.gif'
fatal: unable to checkout working tree
warning: Clone succeeded, but checkout failed.
You can inspect what was checked out with 'git status'
and retry with 'git restore --source=HEAD :/'

This is what I have in my dotspacemacs:

   dotspacemacs-additional-packages
   '(
     (elgantt :location (recipe
                         :fetcher github
                         :repo "legalnonsense/elgantt")))

(defun dotspacemacs/user-config ()
  (require 'elgantt))