a11y issues with links and images on About Us and Contributor pages

[StephNathai]

Describe the bug

• links on the About Us and Contributor pages are not a11y compliant due to: elements must meet minimum contrast ratio thresholds
• member image links on Contributor page are not a11y compliant due to: links must have discernible text

To Reproduce

Steps to reproduce the behavior:

1. Go to https://anitab-org.github.io/ and run a11y audit on the About Us tab and Contributor tab to see the issues called out above in the audit

Expected behavior

• there should be no a11y issues on these page

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[StephNathai]

I will put up a PR shortly to resolve this issue