Fix import of ROOT symbol

Context

IN export_registry.py, the root symbol was included from utils, but it was not defined there, leading to an error.

Fix #35 (closed).

added Fix 🔥🔥 StatusReview Ready labels

requested review from @cmoineau and @wboussella

assigned to @wboussella

changed title from Fix import of ROOR symbol to Fix import of ROOT symbol

approved this merge request

mentioned in commit 100378f4

merged