Update Handlebars

[Mark Hernandez]

GitHub keeps marking this package's handlebars dependency as a security vulnerability.
Would you update it to the appropriate version?

https://david-dm.org/jsdoc2md/dmd

[Lloyd Brookes]

please check closed issues and PRs before posting

[Lloyd Brookes]

handlebars upgraded in the latest release of dmd (v3.0.7).