Technical update

• Simplify usage of CLIVAR ENSO Metrics in PMP by including it as one of PMP conda-forge dependency libraries.
• Improve usability of mean climate metrics when running on external machines.

What's Changed

• Simplify pr variability driver by @lee1043 in #828
• Add enso_metrics by @acordonez in #829
• Lee1043 patch 1 by @lee1043 in #830
• remove black by @lee1043 in #835
• Add shebang to climatologies script by @acordonez in #833
• Update ENSO notebook by @acordonez in #836

Full Changelog: v2.2.1...v2.2.2