Fix Commento top-level comments import

[paskal]

Previously, top-level comments were incorrectly assigned parent comment id "root", which made them non-root, so they are not returned when requested in the /find?format=tree API call.

To fix the previously imported comments, please export all your comments and replace "pid":"root" with "pid":"" and then re-import them.

Resolves #1696.

[github-actions[bot]]

Pull Request Test Coverage Report for Build 6915859953

• 6 of 6 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.04%) to 84.782%

---

Totals
Change from base Build 6756329544:	0.04%
Covered Lines:	5900
Relevant Lines:	6959

---

💛 - Coveralls