Prevent a few make suspicious warnings. (#3341)

Author: ned-deily

Doc/tools/susp-ignored.csv

@@ -325,6 +325,8 @@ whatsnew/3.5,,:warning,'WARNING:root:warning\n'
 whatsnew/3.5,,::,>>> addr6 = ipaddress.IPv6Address('::1')
 whatsnew/3.5,,:root,ERROR:root:exception
 whatsnew/3.5,,:exception,ERROR:root:exception
+whatsnew/changelog,,`,'`'
+whatsnew/changelog,,:end,str[start:end]
 library/binascii,,`,'`'
 library/uu,,`,'`'
 whatsnew/3.7,,`,'`'