Fix Python 3.7 for config_paths

[parasj]

Fixes #667

[sarahwooders]

I'm getting this error on skyplane init and cp:

Traceback (most recent call last):
  File "/Users/sarahwooders/repos/skyplane/env/bin/skyplane", line 5, in <module>
    from skyplane.cli.cli import app
  File "/Users/sarahwooders/repos/skyplane/env/lib/python3.7/site-packages/skyplane/__init__.py", line 3, in <module>
    from skyplane import compute
  File "/Users/sarahwooders/repos/skyplane/env/lib/python3.7/site-packages/skyplane/compute/__init__.py", line 9, in <module>
    from skyplane.compute.gcp.gcp_cloud_provider import GCPCloudProvider
  File "/Users/sarahwooders/repos/skyplane/env/lib/python3.7/site-packages/skyplane/compute/gcp/gcp_cloud_provider.py", line 9, in <module>
    from skyplane.compute.gcp.gcp_network import GCPNetwork
  File "<fstring>", line 1
    (body=)
         ^
SyntaxError: invalid syntax

[parasj]

I can't install Python 3.7 on my Mac as it's ARM. I pushed another change to remove the unsupported fstring syntax. Can you try it one more time? I'm not able to test it locally.

There's a lot of small features that are unsupported on Python 3.7 that I added with the API PR.

[parasj]

(whoops, closed the PR by mistake)

[parasj]

@sarahwooders I think this should fix Python 3.7 issues, but please check if so!

[sarahwooders]

Yep was able to run skyplane init!