add one photon to metadata dict

[bendichter]

OnePhotonSeries is a newer data type, which is why it was not included in the original list

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 88.53%. Comparing base (958adbe) to head (e041653). Report is 4 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1532 +/- ## ========================================== + Coverage 88.45% 88.53% +0.07% ========================================== Files 78 78 Lines 10691 10691 ========================================== + Hits 9457 9465 +8 + Misses 1234 1226 -8 ``` | [Flag](https://app.codecov.io/gh/dandi/dandi-cli/pull/1532/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dandi) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/dandi/dandi-cli/pull/1532/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dandi) | `88.53% <ø> (+0.07%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dandi#carryforward-flags-in-the-pull-request-comment) to find out more.

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[yarikoptic]

thank you!