Marketplace: correct GitHub repo

[mrienstra]

dendron.dendron-paste-image is an official extension, currently associated with mushanshitiancai/vscode-paste-image, which is no longer maintained.

dendron.dendron-paste-image says it was last updated "8/18/2022", which is when this repo was last updated, so clearly this repo is the real power behind the throne. Is it possible to update dendron.dendron-paste-image to point to this repo?

This will reduce confusion, both when new users are evaluating extensions, and when users of this extension wish to report issues.

[mrienstra]

Oh, looks like there's an open PR for this already: #7