Use go 1.16 for race and coverage testing

What does this MR do?

Use the latest supported version of go for race and coverage testing.

Running tests on older version of go to ensure backward compatibility is important, but using the oldest version for race and coverage testing is harmful.

A more concrete example:

From https://golang.org/doc/go1.16:

Go 1.16 fixes a discrepancy between the race detector and the Go memory model. The race detector now more precisely follows the channel synchronization rules of the memory model. As a result, the detector may now report races it previously missed.

TODO

• I added the Changelog (e.g. Changelog: feature) trailer to the commits that need to be included in the changelog
• I added unit tests or they are not required
• I added acceptance tests or they are not required
• I added documentation (or it's not required)
• I followed code review guidelines
• I followed Go Style guidelines