Folder name 'Layer 2:3' is not compatible with Windows

The folder name `Layer 2:3` is not compatible with Windows filesystems. Propose renaming to `Layer 2` consistent with variable naming, e.g.
https://github.com/MetaCell/HNN-UI/blob/bd17a1dd59f12889976739869fe347df3639a6c9/hnn_ui/netParams.py#L45

```
caldw@DESKTOP-LHCRPOM ~/repos$ git clone https://github.com/MetaCell/HNN-UI.git
remote: Enumerating objects: 83, done.
remote: Counting objects: 100% (83/83), done.
remote: Compressing objects: 100% (65/65), done.
remote: Total 1204 (delta 38), reused 43 (delta 17), pack-reused 1121
Receiving objects: 100% (1204/1204), 9.60 MiB | 9.36 MiB/s, done.
Resolving deltas: 100% (579/579), done.
fatal: cannot create directory at 'hnn_ui/metadata/cellParams/Layer 2:3': Invalid argument
warning: Clone succeeded, but checkout failed.
You can inspect what was checked out with 'git status'
and retry the checkout with 'git checkout -f HEAD'
```

There appear to be 3 folders to rename (2 in the first link, 1 in second):
https://github.com/MetaCell/HNN-UI/tree/bd17a1dd59f12889976739869fe347df3639a6c9/hnn_ui/metadata/networkParams
https://github.com/MetaCell/HNN-UI/tree/bd17a1dd59f12889976739869fe347df3639a6c9/hnn_ui/metadata/cellParams