handle ping without timestamp

[kecnry]

Description

This pull request handles the case of multiple tracebacks raised by the ping infrastructure when a popout window sends the ping, but without the timestamp in the payload. It handles this case by assuming the received time as the ping timestamp.

Change log entry

• Is a change log needed? If yes, is it added to CHANGES.rst? If you want to avoid merge conflicts,
  list the proposed change log here for review and add to CHANGES.rst before merge. If no, maintainer
  should add a no-changelog-entry-needed label.

Checklist for package maintainer(s)

This checklist is meant to remind the package maintainer(s) who will review this pull request of some common things to look for. This list is not exhaustive.

• Are two approvals required? Branch protection rule does not check for the second approval. If a second approval is not necessary, please apply the trivial label.
• Do the proposed changes actually accomplish desired goals? Also manually run the affected example notebooks, if necessary.
• Do the proposed changes follow the STScI Style Guides?
• Are tests added/updated as required? If so, do they follow the STScI Style Guides?
• Are docs added/updated as required? If so, do they follow the STScI Style Guides?
• Did the CI pass? If not, are the failures related?
• Is a milestone set? Set this to bugfix milestone if this is a bug fix and needs to be released ASAP; otherwise, set this to the next major release milestone.
• After merge, any internal documentations need updating (e.g., JIRA, Innerspace)?

[pllim]

Looks reasonable. Not sure if we have other choice here when it sends no info. Thanks!

[codecov]

Codecov Report

Patch coverage is 44.82% of modified lines.

Files Changed	Coverage
jdaviz/core/template_mixin.py	0.00%
...nfigs/default/plugins/plot_options/plot_options.py	48.14%

📢 Thoughts on this report? Let us know!.

[camipacifici]

I do not see the warnings anymore! Thank you