Add octavia version to constraints

As we do octavia dashboard bumps, we should provide it's specific version
as a constraint while creating venv

Change-Id: Ie02ef3dd6180128645e4932d50b489f399ea440d
Closes-bug: 1881874
(cherry picked from commit 657648b)

defaults/main.yml

@@ -99,6 +99,7 @@ horizon_git_constraints:
   - "git+{{ horizon_git_repo }}@{{ horizon_git_install_branch }}#egg=horizon"
   - "git+{{ blazar_dashboard_git_repo }}@{{ blazar_dashboard_git_install_branch }}#egg=blazar-dashboard"
   - "git+{{ cloudkitty_dashboard_git_repo }}@{{ cloudkitty_dashboard_git_install_branch }}#egg=cloudkitty_dashboard"
+  - "git+{{ octavia_dashboard_git_repo }}@{{ octavia_dashboard_git_install_branch }}#egg=octavia_dashboard"
   - "git+{{ magnum_dashboard_git_repo }}@{{ magnum_dashboard_git_install_branch }}#egg=magnum-ui"
   - "git+{{ manila_dashboard_git_repo }}@{{ manila_dashboard_git_install_branch }}#egg=manila-ui"
   - "git+{{ masakari_dashboard_git_repo }}@{{ masakari_dashboard_git_install_branch }}#egg=masakari_dashboard"