ZOOKEEPER-3782: Replace filter() with list comprehension for returning list
ZOOKEEPER-3782: Replace filter() with list comprehension for returning list

After Py3, `filter` return a `filter object` instead of `list object`, which causes

```
Traceback (most recent call last):
  File "zk-merge-pr.py", line 533, in <module>
    main()
  File "zk-merge-pr.py", line 519, in main
    resolve_jira_issues(commit_title, merged_refs, jira_comment)
  File "zk-merge-pr.py", line 329, in resolve_jira_issues
    resolve_jira_issue(merge_branches, comment, jira_id)
  File "zk-merge-pr.py", line 312, in resolve_jira_issue
    jira_fix_versions = [get_version_json(v) for v in fix_versions]
  File "zk-merge-pr.py", line 312, in <listcomp>
    jira_fix_versions = [get_version_json(v) for v in fix_versions]
  File "zk-merge-pr.py", line 310, in get_version_json
    return filter(lambda v: v.name == version_str, versions)[0].raw
TypeError: 'filter' object is not subscriptable
```

We can replace filter with list comprehension to fix it.

Author: tison <wander4096@gmail.com>

Reviewers: Enrico Olivelli <eolivelli@apache.org>

Closes #1303 from TisonKun/ZOOKEEPER-3782

maoling/zookeeper,arshadmohammad/zookeeper,apache/zookeeper,arshadmohammad/zookeeper,hanm/zookeeper,hanm/zookeeper,maoling/zookeeper,arshadmohammad/zookeeper,apache/zookeeper,maoling/zookeeper,hanm/zookeeper,apache/zookeeper,hanm/zookeeper,hanm/zookeeper,arshadmohammad/zookeeper,apache/zookeeper,maoling/zookeeper,hanm/zookeeper,apache/zookeeper,apache/zookeeper,hanm/zookeeper,arshadmohammad/zookeeper,maoling/zookeeper,arshadmohammad/zookeeper,hanm/zookeeper,apache/zookeeper,maoling/zookeeper,maoling/zookeeper,apache/zookeeper,arshadmohammad/zookeeper,maoling/zookeeper,arshadmohammad/zookeeper