Fix parse the content for openGraph image for github

[MuhtasimTanmoy]

Fixed

• Description: Invalid response image attribute in case of any GitHub URL

• Issue: Github Repository Image not parsed properly #144

• Commit: 4701a0e

• Changelog

  • Basically, the meta tag containing the target image in GitHub site looks like this. It has no extension as stated below.

  • So, this image pattern used for this particular case cant detect it.

    • static let imagePattern = "(.+?)\\.(gif|jpg|jpeg|png|bmp)$"

  • Also, first checking for "og:image" tag gets the right image as tested.

Sample Meta tag for target image in Github

<meta property="og:image" content="https://opengraph.githubassets.com/404e27b179d006746f87a82d651eba1e24a2dd7babd8
7cb16db0a4d09879e08c/bitcoin/bitcoin" />

[lhunath]

It likely doesn't make sense to try to match this URL against a pattern to try and detect it; instead some tag values should just be assumed to be referencing image URLs without using any pattern testing.