Updates for go1.17

[jmckulk]

Checklist:

• [ ] Have you added an explanation of what your changes do and why you'd like them to be included?
• [ ] Have you updated or added documentation for the change, as applicable? NA
• [ ] Have you tested your changes on all related environments with successful results, as applicable?
  • Built pgBackRest go binary successfully

Type of Changes:

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

What is the current behavior? (link to any open issues here)

What is the new behavior (if this is a feature change)? Go binaries are built using go1.17 (excluding pgBadger that uses a golang:1.15.5 docker image)

Other information: [sc-12565]

[jmckulk]

LGTM. (Separate issue: do we need an "Upgrade" option in our PR template for things like this?)

Oh yeah good idea. Maybe something like

• [ ] Chore or Update (other updates to repository or tools)

[andrewlecuyer]

@benjaminjb @jmckulk lets be sure to bring up the template during our retrospective for the current sprint.

Seems like a good opportunity to review these templates in general to see what makes sense per our current processes.