Add OpenAQ brand images

[jeeftor]

Proposed change

Add OpenAQ brand images for the new openaq core integration.

Source asset:

• OpenAQ logo image: https://user-images.githubusercontent.com/8487728/230648638-35060664-46ef-4d75-9d37-f10dd683b737.png

Type of change

• Add a new logo or icon for a new core integration
• Add a missing icon or logo for an existing core integration
• Add a new logo or icon for a custom integration (custom component)
  • I've added a link to my custom integration repository in the PR description
• Replace an existing icon or logo with a higher quality version
• Replace an existing icon or logo after a branding change
• Removing an icon or logo

Additional information

• This PR fixes or closes issue: fixes #
• Link to code base pull request: Add OpenAQ integration core#169755
• Link to documentation pull request: Add OpenAQ documentation home-assistant.io#45177
• Link to integration documentation on our website:
• Link to custom integration repository:

Checklist

• The added/replaced image(s) are PNG
• Icon image size is 256x256px (icon.png)
• hDPI icon image size is 512x512px for (icon@2x.png)
• Logo image size has min 128px, but max 256px, on the shortest side (logo.png)
• hDPI logo image size has min 256px, but max 512px, on the shortest side (logo@2x.png)