Claiming namespace [google-cloud-spanner-ecosystem]

[olavloite]

• I'm the publisher of https://marketplace.visualstudio.com/items?itemName=google-cloud-spanner-ecosystem.google-cloud-spanner-driver, which uses this namespace
• I'm one of the maintainers of the https://github.com/cloudspannerecosystem organization

[kineticsquid]

@olavloite Thanks for your contribution!