Pa11y testing results
```
> uswds-jekyll@ pa11y-ci:sitemap /home/runner/work/datascience/datascience
> pa11y-ci --sitemap http://localhost:4000/sitemap.xml --sitemap-exclude "/*.pdf"
Running Pa11y on 22 URLs:
(node:2787) UnhandledPromiseRejectionWarning: Error: Page crashed!
at Page._onTargetCrashed (/home/runner/work/datascience/datascience/node_modules/puppeteer/lib/Page.js:215:24)
at CDPSession. (/home/runner/work/datascience/datascience/node_modules/puppeteer/lib/Page.js:123:56)
at CDPSession.emit (events.js:315:20)
at CDPSession._onMessage (/home/runner/work/datascience/datascience/node_modules/puppeteer/lib/Connection.js:200:12)
at Connection._onMessage (/home/runner/work/datascience/datascience/node_modules/puppeteer/lib/Connection.js:112:17)
at WebSocket. (/home/runner/work/datascience/datascience/node_modules/puppeteer/lib/WebSocketTransport.js:44:24)
at WebSocket.onMessage (/home/runner/work/datascience/datascience/node_modules/ws/lib/event-target.js:120:16)
at WebSocket.emit (events.js:315:20)
at Receiver.receiverOnMessage (/home/runner/work/datascience/datascience/node_modules/ws/lib/websocket.js:789:20)
at Receiver.emit (events.js:315:20)
(Use `node --trace-warnings ...` to show where the warning was created)
(node:2787) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:2787) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
> http://localhost:4000/about/people/marlena-medford - 0 errors
> http://localhost:4000/people/jake-rozran - 0 errors
> http://localhost:4000/about/people/daniel-mundra - 0 errors
> http://localhost:4000/posts/hello-world - 0 errors
> http://localhost:4000/projects/usds-dash - 0 errors
> http://localhost:4000/about - 0 errors
> http://localhost:4000/accessibility - 0 errors
> http://localhost:4000/calendar - 0 errors
> http://localhost:4000/colophon - 0 errors
> http://localhost:4000/conduct - 0 errors
> http://localhost:4000/contact - 0 errors
> http://localhost:4000/ - 0 errors
> http://localhost:4000/news/ - 0 errors
> http://localhost:4000/join - 0 errors
> http://localhost:4000/license - 0 errors
> http://localhost:4000/open - 0 errors
> http://localhost:4000/people - 0 errors
> http://localhost:4000/projects - 0 errors
> http://localhost:4000/search - 0 errors
> http://localhost:4000/usdigitalservices.html - 0 errors
> http://localhost:4000/pages/projects/digital_services.html - 7 errors
> http://localhost:4000/people/luke-fretwell - Failed to run
Errors in http://localhost:4000/pages/projects/digital_services.html:
• Buttons must have discernible text
(https://dequeuniversity.com/rules/axe/3.5/button-name?application=axeAPI)
(#navbar > ul:nth-child(2) > li:nth-child(1) > a)
<...
• id attribute value must be unique
(https://dequeuniversity.com/rules/axe/3.5/duplicate-id?application=axeAPI)
()
[no context]
• Document must have one main landmark
(https://dequeuniversity.com/rules/axe/3.5/landmark-one-main?application=axeAPI)
(html)
...
• Zooming and scaling must not be disabled
(https://dequeuniversity.com/rules/axe/3.5/meta-viewport?application=axeAPI)
(html > head > meta:nth-child(6))
• Page must contain a level-one heading
(https://dequeuniversity.com/rules/axe/3.5/page-has-heading-one?application=axeAPI)
(html)
...
• All page content must be contained by landmarks
(https://dequeuniversity.com/rules/axe/3.5/region?application=axeAPI)
(#overview)
Copying the changes merged from https://github.com/CivicActions/datascience_projects/pull/30