Merge ~dbungert/curtin:curtin-build-fix into curtin:master

[Dan Bungert]

deb: fix dependencies

Required for bionic build, also more correct anyhow.

[Server Team CI bot (server-team-bot)]

FAILED: Continuous integration, rev:8e61c23db22f4ac704903ed69751bb8042334b4a
https://jenkins.canonical.com/server-team/job/curtin-ci/11/
Executed test runs:
    FAILURE: https://jenkins.canonical.com/server-team/job/curtin-ci/nodes=metal-amd64/11/
    FAILURE: https://jenkins.canonical.com/server-team/job/curtin-ci/nodes=metal-ppc64el/11/
    FAILURE: https://jenkins.canonical.com/server-team/job/curtin-ci/nodes=metal-s390x/11/

Click here to trigger a rebuild:
https://jenkins.canonical.com/server-team/job/curtin-ci/11//rebuild

review: Needs Fixing (continuous-integration)

[Server Team CI bot (server-team-bot)]

PASSED: Continuous integration, rev:3fcaa5f4a6a45dfdb47d85285906874a2f704ebd
https://jenkins.canonical.com/server-team/job/curtin-ci/12/
Executed test runs:
    SUCCESS: https://jenkins.canonical.com/server-team/job/curtin-ci/nodes=metal-amd64/12/
    SUCCESS: https://jenkins.canonical.com/server-team/job/curtin-ci/nodes=metal-ppc64el/12/
    SUCCESS: https://jenkins.canonical.com/server-team/job/curtin-ci/nodes=metal-s390x/12/

Click here to trigger a rebuild:
https://jenkins.canonical.com/server-team/job/curtin-ci/12//rebuild

review: Approve (continuous-integration)

[Michael Hudson-Doyle (mwhudson)]

Thanks.

review: Approve

diff --git a/debian/control b/debian/control
index 72bb6cc..a35cbf6 100644
--- a/debian/control
+++ b/debian/control
@@ -7,6 +7,7 @@ Build-Depends: debhelper (>= 7),
                dh-python,
                python3,
                python3-apt,
+               python3-attr,
                python3-coverage,
                python3-mock,
                python3-nose,
@@ -53,6 +54,7 @@ Architecture: all
 Priority: extra
 Depends: curtin-common (= ${binary:Version}),
          python3-apt,
+         python3-attr,
          python3-oauthlib,
          python3-yaml,
          wget,