Units of `tau_osm` and `tau_noc` are incrrect

The Units of `tau_osm` at [canopylayer.jl#L163](https://github.com/CliMA/Land/blob/main/src/StomataModels/types/canopylayer.jl#L163) is incorrectly listed as `[μmol⁻¹]`.
The units of `tau_osm` should be `[mol² m⁻² s⁻² μmol⁻¹]` based on the following calculation:
```
d(g_sw)/dt = [mol m⁻² s⁻¹]/s = [mol m⁻² s⁻²]
(dA/dE – d\Theta/dE) = [μmol m⁻² s⁻¹] / [mol m⁻² s⁻¹] = [μmol mol⁻¹]
tau_osm = [mol² m⁻² s⁻² μmol⁻¹]
```

Open src/StomataModels/types/canopylayer.jl at line 163 and compare the tau_osm unit annotation with the dimensional calculation in the issue. Correct the documented units and inspect the nearby tau_noc annotation mentioned in the title, then verify the source reflects the intended dimensions.

Written by the indexing model from the issue text.