pyupgrade: Reformat with --py36-plus.

This includes mainly fixes of string literals using f-strings or
.format(...), as well as unpacking of list comprehensions.

zulip/integrations/openshift/zulip_openshift_config.py

@@ -21,7 +21,7 @@ ZULIP_API_KEY = "0123456789abcdef0123456789abcdef"
 # And similarly for branch "test-post-receive" (for use when testing).
 def deployment_notice_destination(branch: str) -> Optional[Dict[str, str]]:
     if branch in ["master", "test-post-receive"]:
-        return dict(stream="deployments", subject="%s" % (branch,))
+        return dict(stream="deployments", subject=f"{branch}")
 
     # Return None for cases where you don't want a notice sent
     return None
@@ -46,7 +46,7 @@ def format_deployment_message(
     dep_id: str = "",
     dep_time: str = "",
 ) -> str:
-    return "Deployed commit `%s` (%s) in [%s](%s)" % (commit_id, branch, app_name, url)
+    return f"Deployed commit `{commit_id}` ({branch}) in [{app_name}]({url})"
 
 
 ## If properly installed, the Zulip API should be in your import