[DM] Network template incorrectly handles empty networks (#507)
[DM] Network template incorrectly handles empty networks (#507)

* Fixes #506: Network template incorrectly handles empty networks
https://github.com/GoogleCloudPlatform/cloud-foundation-toolkit/issues/506

Removed oneOf from network.py.schema.

* update network schema version

GoogleCloudPlatform/cloud-foundation-toolkit,GoogleCloudPlatform/cloud-foundation-toolkit,GoogleCloudPlatform/cloud-foundation-toolkit,GoogleCloudPlatform/cloud-foundation-toolkit,GoogleCloudPlatform/cloud-foundation-toolkit