script: Fix copyright_header.py

This change prevents updating copyright years from "2021" to
"2021-2017".

Author: hebasto

contrib/devtools/copyright_header.py

@@ -371,7 +371,7 @@ def create_updated_copyright_line(line, last_git_change_year):
     space_split = after_copyright.split(' ')
     year_range = space_split[0]
     start_year, end_year = parse_year_range(year_range)
-    if end_year == last_git_change_year:
+    if end_year >= last_git_change_year:
         return line
     return (before_copyright + copyright_splitter +
             year_range_to_str(start_year, last_git_change_year) + ' ' +