chore: update source repository for the jsonnet-tool asdf plugin
The jsonnet-tool installation and management is now part of the asdf-gl-infra[1] plugin.
Thus, update link to the source repository to reflect asdf plugin change, and ensure that jsonnet-tool will be installed using the new plugin going forward.
While at it, ensure that existing installation of the jsonnet-tool plugin are migrated to the new asdf plugin as needed.
Signed-off-by: Krzysztof Wilczyński kwilczynski@gitlab.com