requirements: Upgrade yamole to 2.1.5.

requirements/common.in

@@ -198,4 +198,4 @@ django-sendfile==0.3.11
 disposable-email-domains==0.0.28
 
 # Needed for parsing YAML with JSON references from the REST API spec files
-yamole==2.1.2
+yamole==2.1.5

requirements/dev.txt

@@ -181,5 +181,5 @@ websocket-client==0.44.0  # via docker
 werkzeug==0.12.2          # via moto
 wrapt==1.10.11            # via aws-xray-sdk
 xmltodict==0.11.0         # via moto
-yamole==2.1.2
+yamole==2.1.5
 zope.interface==4.4.3     # via twisted

requirements/prod.txt

@@ -123,4 +123,4 @@ urllib3==1.22             # via requests
 uwsgi==2.0.17
 virtualenv-clone==0.3.0
 wcwidth==0.1.7            # via prompt-toolkit
-yamole==2.1.2
+yamole==2.1.5

version.py

@@ -8,4 +8,4 @@ ZULIP_VERSION = "1.8.1+git"
 # Typically, adding a dependency only requires a minor version bump, and
 # removing a dependency requires a major version bump.
 
-PROVISION_VERSION = '20.10'
+PROVISION_VERSION = '20.11'