SEO Tweaks for Gas Tracker Page

[isstuev]

Description and Related Issue(s)

resolves https://github.com/blockscout/frontend/issues/2340

Checklist for PR author

• [ ] I have tested these changes locally.
• [ ] I added tests to cover any new functionality, following this guide
• [ ] Whenever I fix a bug, I include a regression test to ensure that the bug does not reappear silently.
• [ ] If I have added, changed, renamed, or removed an environment variable
  • I updated the list of environment variables in the documentation
  • I made the necessary changes to the validator script according to the guide
  • I added "ENVs" label to this pull request