Update docstrings for pandas 3

[jsignell]

I still need to figure out how to make CI use pandas 3, but this passes doctests locally.

• Closes Doctests don't pass with pandas 3 #11129

[jsignell]

@VeckoTheGecko it looks like the "dynamic" version in pixi.toml prevents installing newer versions of pandas. This is the error when I tried to force it like I did in 67f3423:

Error:   × failed to solve requirements of environment 'test-py313-pandas-3' for platform 'osx-arm64'
  ├─▶   × failed to solve the environment
  │   
  ╰─▶ Cannot solve the request because of: The following packages are incompatible
      ├─ xarray * can be installed with any of the following options:
      │  └─ xarray dynamic
      └─ pandas 3.0.* cannot be installed because there are no viable options:
         └─ pandas 3.0.0 | 3.0.0 | 3.0.0 | 3.0.0 | 3.0.0 would constrain
            └─ xarray >=2024.10.0, which conflicts with any installable versions previously reported

If I set the version string to something. For instance: 2026.02.0.dev then it works fine

[VeckoTheGecko]

interesting, will try dedicate some time this week to look into it

[kkollsga]

I looked into this - pixi doesn't support dynamic versioning yet, so version = "dynamic" is treated as a literal string.

pandas 3 has constrains: xarray >= 2024.10.0 (optional dependency), so when both are in the environment the solver compares "dynamic" >= "2024.10.0" and fails. (Related: prefix-dev/pixi#2923)

Using 2026.02.0.dev as a placeholder version in pixi.toml works. With monthly CalVer releases it may need occasional updates - using 9999.0.0 instead would avoid that, but either is fine since setuptools_scm provides the real version from git tags at install time.

[jsignell]

I updated to using 9999.0.0 as @kkollsga suggested. Looks like everything is working fine.

[jsignell]

Merging commits from #11138 into this branch which also updates cfgrib (#11138 (comment))