slapos_web_deploy: Use shacache source

github.com might be not available in many places.

master/bt5/slapos_web_deploy/PathTemplateItem/web_page_module/deploy_base_setup.txt

@@ -252,7 +252,7 @@ ansible localhost -m pip -a name=slapcache --connection=local
 ansible localhost -m pip -a name=requests --connection=local
 
 if [ ! -f /usr/share/ansible_plugins/mitogen.zip ]; then
-    wget -O /usr/share/ansible_plugins/mitogen.zip https://github.com/dw/mitogen/archive/2d7821b824a77930812847c87ea385cf37198c3f.zip
+    wget -O /usr/share/ansible_plugins/mitogen.zip https://shacache.nxdcdn.com/3a935ff257ddc0ad4e0f23d71681e026f14f309f4bed0a8e2a217da9b294be2c676196703f0dde856ece49d711d0221deae70812f035b24aa5cdd0ca02790e85
     unzip /usr/share/ansible_plugins/mitogen.zip -d /usr/share/ansible_plugins/mitogen/
     mv /usr/share/ansible_plugins/mitogen/mitogen-*/* /usr/share/ansible_plugins/mitogen/
 fi