[Requirements] FIX: Upgrade ebaysdk to 2.1.5 due to bug

Upgrade the dependency for ebaysdk from 2.1.4 to 2.1.5.
There was a bug in in 2.1.4 that prevented installing (see https://github.com/timotheus/ebaysdk-python/issues/223).
Closes #20148 

requirements.txt

 Babel==2.3.4
 decorator==4.0.10
 docutils==0.12
-ebaysdk==2.1.4
+ebaysdk==2.1.5
 feedparser==5.2.1
 gevent==1.1.2
 greenlet==0.4.10