Update version to 1.3.0-dev

[ukclivecox]

What this PR does / why we need it:
Update to 1.3.0-dev version
Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

[review-notebook-app]

Check out this pull request on 

Review Jupyter notebook visual diffs & provide feedback on notebooks.

---

Powered by ReviewNB

[seldondev]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by:
To complete the pull request process, please assign cliveseldon
You can assign the PR to them by writing /assign @cliveseldon in a comment when ready.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[seldondev]

Thu Jul 30 12:11:53 UTC 2020
The logs for [lint] [2] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-2219/2.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2219 --build=2

[seldondev]

Thu Jul 30 12:12:11 UTC 2020
The logs for [pr-build] [1] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-2219/1.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2219 --build=1