Atualiza packtools versão 4.15.0 (#1358)

Author: robertatakenaka

requirements/base.txt

@@ -88,7 +88,7 @@ pysolr==3.9.0  # https://pypi.org/project/pysolr/
 # ------------------------------------------------------------------------------
 tornado>=6.5.2 # not directly required, pinned by Snyk to avoid a vulnerability 
 lxml==6.0.2  # https://github.com/lxml/lxml
-git+https://git@github.com/scieloorg/packtools@4.14.0#egg=packtools
+git+https://git@github.com/scieloorg/packtools@4.15.0#egg=packtools
 
 # pymongo
 # ------------------------------------------------------------------------------