Update ruby gems; update rexml gem to patch CVE (#40)

* Update ruby gems; update rexml gem to patch CVE

* Run tests against greater number of platforms and operating systems

Update ruby gems

Update ruby gems

Update ruby gems

DRY up shared examples

Update ruby gems and bump version

Ruby gem updates bump to version 3.0.2

Update version and CHANGELOG.md

Bump the development-dependencies group with 1 update (#4)

* Bump the development-dependencies group with 1 update

Updates the requirements on [simplecov](https://github.com/simplecov-ruby/simplecov) to permit the latest version.
- [Release notes](https://github.com/simplecov-ruby/simplecov/releases)
- [Changelog](https://github.com/simplecov-ruby/simplecov/blob/main/CHANGELOG.md)
- [Commits](simplecov-ruby/simplecov@v0.21.2...v0.22.0)

---
updated-dependencies:
- dependency-name: simplecov
  dependency-type: direct:development
  update-type: version-update:semver-minor
  dependency-group: development-dependencies
...

Signed-off-by: dependabot[bot] <[email protected]>

* Update CHANGELOG.md

---------

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: gangelo <[email protected]>

v2.0.0 (#2)

* Changes
  * Add spec coverage.
  * Update README.md.
* Breaking change
  * Remove unused Module HashRetrievable.
* Bug Fixes
  * Fix bug that raised an error when :namespace
option is not a Symbol due cut & paste error from
validation routine that checked the :metadata
option for validity.
  * Fix bug when checking
`MadFlatter::Service#options.namespace? an error
was raised if option :namespace was not passed
as an option since it is optional.