Add NCO spec to conda dev file

[forsyth2]

Summary

Objectives:

• Specify NCO explicitly in the conda dev file

Issue resolution:

• Closes [Bug]: e3sm_to_cmip failing due to srun error #875

Select one: This pull request is...

• a bug fix: increment the patch version
• a small improvement: increment the minor version
• a new feature: increment the minor version
• an incompatible (non-backwards compatible) API change: increment the major version

Small Change

• To merge, I will use "Squash and merge". That is, this change should be a single commit.
• Logic: I have visually inspected the entire pull request myself.
• Pre-commit checks: All the pre-commits checks have passed.

[forsyth2]

Closing per my comment here. zppy does not actually use NCO, which is why it was never defined here. zppy only defines run_nco function and nco_path parameter to switch the path used for it for multiple called tasks.