move to maintained fork of mapstructure

[jm96441n]

Description

the mitchelh/matpstructure repo is being archived (see https://gist.github.com/mitchellh/90029601268e59a29e64e55bab1c5bdc) the go-viper fork is the maintained one https://github.com/go-viper/mapstructure?tab=readme-ov-file#migrating-from-githubcommitchellhmapstructure there should be no code changes required just changing the dependency

Testing & Reproduction steps

Links

PR Checklist

• [ ] updated test coverage
• [ ] external facing docs updated
• [ ] appropriate backport labels added
• [ ] not a security concern