Reverted hover color on drop-down to gray

[ankurg22]

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Changes done in this Pull Request

• Currently, the hover color was red. Since we are not following FOSSASIA's standard so red didn't make any sense. So reverted it to gray.
• https://ankurg22.github.io/gci17.fossasia.org/
• Fixes #971

[yashLadha]

Ping @mariobehling

[ankurg22]

@ParthS007 Made the changes please review.

[ankurg22]

@yashLadha @rupav @ParthS007 Why isn't the change of this PR reflecting back on the website? It is working fine on my machine and on my forked repo gh-pages site.

[rupav]

@ankurg22 it takes sometime time to build gh-pages. You can expect changes within few hours in original website.