refactor: don't use shell.openExternal in renderer

[dsanders11]

All window.open calls are already denied and opened by shell.openExternal by default via setWindowOpenHandler, so shell.openExternal doesn't need to be used in the renderer.

fiddle/src/main/windows.ts

Lines 89 to 92 in ff0de26

	browserWindow.webContents.setWindowOpenHandler((details) => {
	shell.openExternal(details.url);
	return { action: 'deny' };
	});

[coveralls]

Coverage: 91.379% (-0.004%) from 91.382% when pulling 9044272 on dsanders11:contributors-open into ff0de26 on electron:main.