Toolkit page: Make the External Resources section cards' SVGs WCAG compliant

### Dependencies
- [ ] When we are ready to prioritize the toolkit again
- [x] #3879

### Overview
We need to make the Scalable Vector Graphics (SVGs) in the Toolkit webpage's External Resources section Web Content Accessibility Guidelines (WCAG) compliant so that we can achieve our mission of inclusivity.

### Action Items
- [ ] Read the wiki article for How to make SVGs and other images WCAG compliant [See 2 in Resources/Instructions section below]
- [ ] Apply what you learned from the wiki article to the SVGs in the External Resources section of the Toolkit webpage by editing `pages/toolkit.html` file.
- [ ] All the External Resources images (Figma, GitHub, Zoom) are decorative, so they should have `aria-label=""` if using ARIA labels or `alt=""` attribute if using `img` HTML tags
- [ ] Make sure the code you implement is dynamic so that it works for SVGs added to the External Resources section in the future

### Resources/Instructions
1. [Toolkit](https://www.hackforla.org/toolkit) page's External Resources section
2. Link to wiki article for [How to make SVGs and other images WCAG compliant](https://github.com/hackforla/website/wiki/How-to-make-SVGs-and-other-images-WCAG-compliant)
3. [pages/toolkit.html](https://github.com/hackforla/website/blob/gh-pages/pages/toolkit.html)
4. This issue is a result of issue #2567