New Sentinel-2 collection name (#2421)

* change example and default script with new S2 collection name

* fix format

experiments/ssl4eo/download_ssl4eo.py

@@ -12,7 +12,7 @@
 ### match and download pre-sampled locations
 python download_ssl4eo.py \
     --save-path ./data \
-    --collection COPERNICUS/S2 \
+    --collection COPERNICUS/S2_HARMONIZED \
     --meta-cloud-name CLOUDY_PIXEL_PERCENTAGE \
     --cloud-pct 20 \
     --dates 2021-12-21 2021-09-22 2021-06-21 2021-03-20 \
@@ -319,7 +319,10 @@ def update(self, delta: int = 1) -> int:
     )
     # collection properties
     parser.add_argument(
-        '--collection', type=str, default='COPERNICUS/S2', help='GEE collection name'
+        '--collection',
+        type=str,
+        default='COPERNICUS/S2_HARMONIZED',
+        help='GEE collection name',
     )
     parser.add_argument('--qa-band', type=str, default='QA60', help='qa band name')
     parser.add_argument(