Upgrade stretchr/testify dependency to fix security issue in gopkg.in…

…/yaml.v3 (#23)

Fix JSON unmarshalling in complex structures bug (#22)

* Add documentation in README about JSON marshalling

Add support for JSON marshalling (#21)

Fix use of "contraints" package and update GitHub action

* Update go.yml

* Fix comparison.go use of constraints

Documentation fixes

* Fix the documentation of some comparison functions
* Add package documentation

The first release of `go-tuple`.

`go-tuple` follows [semantic versioning](https://semver.org/).
This means:

* Incompatible API changes that are not backwards compatible will bump the "major" version, and reset the "minor" and "patch" versions.
* New features that are backwards-compatible will bump the "minor" version and reset the "patch" version.
* Bug fixes that are backwards-compatible will bump the "patch" version.

Supported features:
* Tuples can contain values of different types.
* Support tuples with a varying number of values, from 1 to 9.
* Tuples can be constructed with the `New*` function.
* Tuples implement the `Stringer` and `GoStringer` interfaces.
* Tuples of the same type can be compared and ordered.