Permit a scalar type for T in iter.SQL

[bobg]

This PR expands iter.SQL, permitting its type parameter optionally to be a scalar instead of a struct, in the case where the db query produces a single value per row.

[github-actions]

Modver result

This report was generated by Modver,
a Go package and command that helps you obey semantic versioning rules in your Go module.

This PR requires (at least) an increase in your module's patchlevel.

checking keyedSorter
  old and new versions of github.com/bobg/go-generics/v3/slices.keyedSorter[S ~[]T, T any] are not identical
    Patchlevel

[coveralls]

Pull Request Test Coverage Report for Build 9823633326

Details

• 18 of 22 (81.82%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.2%) to 87.854%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
iter/sql.go	18	22	81.82%

Totals
Change from base Build 9142844186:	-0.2%
Covered Lines:	1056
Relevant Lines:	1202

---

💛 - Coveralls