T15006: Update .arcconfig to point to we.phorge.it
Summary:
Update the `.arcconfig` file to point to our decided-upon URL for hosting
Refs T15006
Test Plan:
I used `arc which` and verified it identified `https://we.phorge.it`:
```lang=console
REPOSITORY
To identify the repository associated with this working copy, arc followed this process:
Configuration value "repository.callsign" is empty.
This repository has no VCS UUID (this is normal for git/hg).
The remote URI for this working copy is
"ssh://git@we.phorge.it/source/phorge.git".
Found a unique matching repository.
This working copy is associated with the Phorge repository.
```
Reviewers: avivey, chris, tobiaswiese
Reviewed By: avivey, tobiaswiese
Maniphest Tasks: T15006
Differential Revision: https://we.phorge.it/D25001