chore(#644): Upgrade python templates to use RemoteBackend class

[bradseiler]

Addresses issue #644

Tested locally by initializing the python template project and successfully generating the cdk.tf.json output:

{
  "//": {
    "metadata": {
      "version": "0.0.0",
      "stackName": "python-example"
    }
  },
  "terraform": {
    "backend": {
      "remote": {
        "organization": "bradseiler-test",
        "workspaces": {
          "name": "python"
        },
        "hostname": "app.terraform.io"
      }
    }
  }
}

[hashicorp-cla]

All committers have signed the CLA.

[skorfmann]

@bradseiler thanks for the fix - please make sure to sign the CLA - we can't merge without this.

[bradseiler]

Thanks @skorfmann, we just executed a corporate CLA between Square and Hashicorp, @cneralich should have it. I'm submitting this as a work product on behalf of Square.

[danieldreier]

Thanks @bradseiler! I'm investigating why the CLA approval hasn't come through yet, and am excited to get this fix merged. Thank you for contributing!

[danieldreier]

@bradseiler I followed-up and we got the CLA authorization sorted out, so I was able to merge this. Thank you for this fix!

[github-actions]

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