License checker: Replace incorrect push with append (#1268)

Replace incorrect `push` with `append`

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

scripts/check-license/src/check_license/copyright.py

@@ -44,7 +44,7 @@ def push_year(self, year: int) -> None:
         if year == self.years[-1].end + 1:
             self.years[-1].end = year
         else:
-            self.years.push(Years(year, year))
+            self.years.append(Years(year, year))
 
 
 @dataclasses.dataclass