fix invalid pseudo version

[minchao]

Related issue

When on go 1.13.x:

$ go clean -modcache
$ go mod download
go: github.com/ory/[email protected] requires
	cloud.google.com/[email protected] requires
	github.com/googleapis/gax-go/[email protected] requires
	google.golang.org/[email protected] requires
	github.com/golang/[email protected]: invalid pseudo-version: does not match version-control timestamp (2018-12-17T17:45:47Z)

See the Go release notes about the "Version validation":

The date string must match the UTC timestamp of the revision.

Proposed changes

Change to the correct pseudo version.

Checklist

• I have read the contributing guidelines
• I have read the security policy
• I confirm that this pull request does not address a security vulnerability. If this pull request addresses a security
  vulnerability, I confirm that I got green light (please contact [email protected]) from the maintainers to push the changes.
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation within the code base (if appropriate)
• I have documented my changes in the developer guide (if appropriate)

[aeneasr]

Thanks!