update vulnerable dependency

[gfrankliu]

Trivy scanner reports os pulls vulnerable rake, probably due to https://github.com/rdp/os/blob/master/Gemfile.lock#L11

==================================================
Total: 1 (UNKNOWN: 0, LOW: 0, MEDIUM: 0, HIGH: 1, CRITICAL: 0)

+---------+------------------+----------+-------------------+---------------+--------------------------------------+
| LIBRARY | VULNERABILITY ID | SEVERITY | INSTALLED VERSION | FIXED VERSION |                TITLE                 |
+---------+------------------+----------+-------------------+---------------+--------------------------------------+
| rake    | CVE-2020-8130    | HIGH     | 0.9.6             | 12.3.3        | rake: OS Command Injection           |
|         |                  |          |                   |               | via egrep in Rake::FileList          |
|         |                  |          |                   |               | -->avd.aquasec.com/nvd/cve-2020-8130 |
+---------+------------------+----------+-------------------+---------------+--------------------------------------+