[Jira] Issue in get_issue_changelog with advanced_mode=True

Module: jira.py
Function: get_issue_changelog
Line: `return (self.get(url) or {}).get("changelog")`
Error Message: 'Response' object has no attribute 'get'

Pseudo Example
```
jira = Jira(
        url="https://jira.example.com/", 
        username="user",
        password="pass",
        advanced_mode=True
    )

jira.get_issue_changelog("TEST-1234")
```


