Update fastly_exporter to 8.1.0

[github-actions]

Update fastly_exporter to 8.1.0.

What's Changed

New Features 🎉

• Implement aggregated datacenter metrics by @mikelorant in Implement aggregated datacenter metrics fastly/fastly-exporter#153

Dependencies

• Bump github.com/prometheus/client_golang from 1.19.0 to 1.19.1 by @dependabot in Bump github.com/prometheus/client_golang from 1.19.0 to 1.19.1 fastly/fastly-exporter#166

Other Changes

• Fix aggregated domain metrics test fixture by @mikelorant in Fix aggregated domain metrics test fixture fastly/fastly-exporter#168
• Refactor metrics processing by @mikelorant in Refactor metrics processing fastly/fastly-exporter#169

New Contributors

• @mikelorant made their first contribution in Fix aggregated domain metrics test fixture fastly/fastly-exporter#168

Full Changelog: fastly/fastly-exporter@v8.0.0...v8.1.0