Version 4 API for Go 1.23

[bobg]

This PR updates go-generics to new major version 4 for the release of Go 1.23.

Version 4 removes the iter and maps packages.

The iter.Of[T] type was made obsolete with the introduction of Go 1.23 iterators. The functionality previously available for iter.Of[T] iterators has now been replicated for Go 1.23 iterators in the github.com/bobg/seqs package (qv).

The maps package was mostly redundant with the Go standard library.

Additionally, combinatorial operations previously found in the slices package have now moved to github.com/bobg/combo.

[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 an increase in your module’s major version number.
If the new major version number is 2 or greater,
you must also add or update the version suffix
on the module path defined in your go.mod file.
See the Go Modules Reference for more info.

no new version of package github.com/bobg/go-generics/v3/iter
  Major

[github-actions]

Pull Request Test Coverage Report for Build 10398031835

Details

• 89 of 95 (93.68%) changed or added relevant lines in 4 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+3.3%) to 91.188%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
parallel/parallel.go	9	12	75.0%
slices/slices.go	41	44	93.18%

Files with Coverage Reduction	New Missed Lines	%
parallel/parallel.go	1	79.17%

Totals
Change from base Build 10237406652:	3.3%
Covered Lines:	476
Relevant Lines:	522

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💛 - Coveralls