Add depth-estimation task category to metadata

This PR improves the dataset card for PrediTree by adding `depth-estimation` to the `task_categories` in the metadata.

The dataset is explicitly designed for "training and evaluating tree height prediction models" and to "predict the canopy height", making `depth-estimation` the most appropriate task category for its discoverability and classification on the Hugging Face Hub.

README.md

@@ -1,4 +1,8 @@
 ---
+license: apache-2.0
+pretty_name: PrediTree
+task_categories:
+- depth-estimation
 dataset_info:
   features:
   - name: id
@@ -65,8 +69,6 @@ configs:
   data_files:
   - split: train
     path: data/train-*
-license: apache-2.0
-pretty_name: PrediTree
 tags:
 - remote-sensing
 - multi-temporal