Aeronet-header-fix to handle V3 data (#4101)

Co-authored-by: Valeriu Predoi <valeriu.predoi@gmail.com>

Author: nchawang

esmvaltool/cmorizers/data/formatters/datasets/aeronet.py

@@ -34,7 +34,7 @@
 
 logger = logging.getLogger(__name__)
 
-AERONET_HEADER = "AERONET Version 3;"
+AERONET_HEADER = "AERONET Version 3"
 LEVEL_HEADER = "Version 3: AOD Level 2.0"
 LEVEL_DESCRIPTION = (
     "The following data are automatically cloud cleared and quality assured "