Describe the issue

When merging coco annotations using merge_coco_annotations, the resulting annotation file's annotation list skips an id at the merge point (IE it jumps from 5 to 7).
I think the only change needed is to remove the + 1 from https://github.com/DLR-RM/BlenderProc/blob/main/blenderproc/python/writer/CocoWriterUtility.py#L278. annotation["id"] is indexed starting at 1, so right now the first annotation in the target gets assigned 1 + max(annotation["id"] for annotation in existing_coco_annotations["annotations"]) + 1, or 2 more than the max of the original.

Minimal code example

No response

Files required to run the code

No response

Expected behavior

Expected: annotation ids seamlessly increment through the merged coco_annotations.
Actual: annotation ids skip a number at the merge point.

BlenderProc version

Version 2.5.0 20th September 2022