chore: release 1.4.0

[release-please[bot]]

:robot: I have created a release *beep* *boop*

1.4.0 (2021-02-17)

Features

• add suport for setting enable_endpoint_independent_mapping options (#46) (1df7c42)

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[release-please[bot]]

:robot: Release is at https://github.com/terraform-google-modules/terraform-google-cloud-nat/releases/tag/v1.4.0 :sunflower: