User and Post Services: Replace Exec() with ExecContext()

[codegold79]

In the qryuser.go and qrypost.go files, the Exec() methods should be replaced with ExecContext(). The reason for this is to be able to take advantage of the the cancellation/timeout that contexts can initiate.

See an example of ExecContext() in the upsertUser method in qryuser.go.

A/C

• Replace Exec() with ExecContext() in the user and post service queries
• Ensure the artefact tests pass after the changes

[daved]

Sure, sounds good. I think the main takeaway will be having the project building and tests running. I expect I'll have a story or two blocking (probably the actions bot issue, at least).