• Remove < 1.13 and possibly < 1.16
• Add 1.18

The current CircleCi config fails when Go 1.18 is added.

See related

• Check for and report bad protocol in TLSClientConfig.NextProtos #788 (requires Go >= 1.13)
• Replaced the deprecated ioutil package #776 (requires Go >= 1.16)
• test for github actions and remove old golang version #778 (edits CircleCI config, adds GitHub action)

I do not have time to work on this. It will be great if somebody else can investigate.