Add Repository to the RepositoryVulnerabilityAlertEvent struct

[ryanwi]

The RepositoryVulnerabilityAlertEvent payload includes the Repository key which is important to add context to the Alert. The alert by itself does not capture what repo the alert is on.

https://developer.github.com/v3/activity/events/types/#repositoryvulnerabilityalertevent

{
    "action": "create",
    "alert": {
      "id": 271940701,
      "affected_range": "< 2.2.3",
      "affected_package_name": "https-proxy-agent",
      "external_reference": "https://github.com/TooTallNate/node-https-proxy-agent/commit/36d8cf509f877fa44f4404fce57ebaf9410fe51b",
      "external_identifier": "WS-2019-0310",
      "ghsa_id": "GHSA-pc5p-h8pf-mvwp",
      "created_at": "2020-04-16T22:28:10Z",
      "fixed_in": "2.2.3"
    },
    "repository": {
// repo details here
    }

[googlebot]

Thanks for your pull request. It looks like this may be your first contribution to a Google open source project (if not, look below for help). Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

📝 Please visit https://cla.developers.google.com/ to sign.

Once you've signed (or fixed any issues), please reply here with @googlebot I signed it! and we'll verify it.

---

What to do if you already signed the CLA

Individual signers

• It's possible we don't have your GitHub username or you're using a different email address on your commit. Check your existing CLA data and verify that your email is set on your git commits.

Corporate signers

• Your company has a Point of Contact who decides which employees are authorized to participate. Ask your POC to be added to the group of authorized contributors. If you don't know who your Point of Contact is, direct the Google project maintainer to go/cla#troubleshoot (Public version).
• The email used to register you as an authorized contributor must be the email used for the Git commit. Check your existing CLA data and verify that your email is set on your git commits.
• The email used to register you as an authorized contributor must also be attached to your GitHub account.

ℹ️ Googlers: Go here for more info.

[gmlewis]

Thank you, @ryanwi.

Two things need to be done before we can move forward with this (see CONTRIBUTING.md for more details):

• go generate ./...
• sign the Google CLA

[googlebot]

CLAs look good, thanks!

ℹ️ Googlers: Go here for more info.

[codecov]

Codecov Report

Merging #1496 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1496   +/-   ##
=======================================
  Coverage   68.19%   68.19%           
=======================================
  Files          94       94           
  Lines        8452     8452           
=======================================
  Hits         5764     5764           
  Misses       1819     1819           
  Partials      869      869           

Impacted Files	Coverage Δ
github/event_types.go	100.00% <ø> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 4ca0dcc...2cecaa5. Read the comment docs.

[gmlewis]

Thank you, @ryanwi!
LGTM.
Merging.

[ryanwi]

Wow, that was fast @gmlewis, thank you!

[gmlewis]

Thank you, @ryanwi! We appreciate all contributions to help keep this repo up-to-date.