Update Gemfile to metasploit_data_models 0.6.2

[#45816713]

0.6.2 fixes Mdm::WebVuln#confidence erroroneously not accepting a value
of 0.
Update gemcache to metasploit_data_models 0.6.2
updated mdm
Merge pull request #1564 from rapid7/feature/metasploit_data_models-0.6.2

Update to metasploit_data_models 0.6.2