Update dependency numpy to v1.21.1

Author: renovate-bot

requirements.txt

@@ -1,7 +1,7 @@
 elasticsearch==7.6.0
 elasticsearch-dsl==7.1.0
 jenkspy==0.1.5
-numpy==1.18.3
+numpy==1.21.1
 pandas==1.0.3
 python-dateutil==2.8.1
 pytz==2020.1