fix: add the wgs namespace binding back

[aucampia]

Summary of changes

#1686 inadvertently removed the wgs prefix.
This change adds it back.

• Closes Shipped namespace bindings missing/misspelled #2196.

Checklist

• Checked that there aren't other open pull requests for
  the same change.
• Added tests for any changes that have a runtime impact.
• Checked that all tests and type checking passes.
• Considered granting push permissions to the PR branch,
  so maintainers can fix minor issues and keep your PR up to date.

[aucampia]

Planning to merge this by 2023-03-21.

[coveralls]

Coverage: 90.782%. Remained the same when pulling 6c1d9e8 on aucampia:iwana-20230319T1901-wgs_namespace into 5a80926 on RDFLib:main.

[aucampia]

@nicholascar it would be good to get your input here, should we change sdo back to schema?

[aucampia]

Another related regression is:

• dcterms no longer included among default namespaces in 6.2.0 #2103

I'm going to create a mailing list post to get some feedback.

[aucampia]

I'm going to rework this change to only add wgs back, I guess that is not too convroversial, I'm not going to fix the https://schema.org thing without clear consensus in this discussion: https://groups.google.com/g/rdflib-dev/c/2Dg7MkldV1c.

[ghost]

👍