ARROW-8016: [Developer] Fix jira-python deprecation warning in merge_…

…arrow_pr.py

This squelches the warning for me. I merged a PR using this revision

Closes #6552 from wesm/ARROW-8016 and squashes the following commits:

dc9a265 <Wes McKinney> Fix jira-python deprecation warning

Authored-by: Wes McKinney <wesm+git@apache.org>
Signed-off-by: Wes McKinney <wesm+git@apache.org>

dev/merge_arrow_pr.py

@@ -518,7 +518,7 @@ def get_credentials(cmd):
 
 def connect_jira(cmd):
     try:
-        return jira.client.JIRA({'server': JIRA_API_BASE},
+        return jira.client.JIRA(options={'server': JIRA_API_BASE},
                                 basic_auth=get_credentials(cmd))
     except jira.exceptions.JIRAError as e:
         if "CAPTCHA_CHALLENGE" in e.text: