Deps: Minimize list of dependencies

[trakhimenok]

See go.mod.

Candidates for removal:

• github.com/google/uuid v1.3.0 // indirect
• github.com/julienschmidt/httprouter v1.3.0 // indirect
• github.com/pquerna/ffjson v0.0.0-20190930134022-aa0246cd15f7 // indirect
• github.com/strongo/app v0.1.0 // indirect
• github.com/strongo/emoji v0.0.1 // indirect
• github.com/strongo/gamp v0.0.1 // indirect
• github.com/strongo/log v0.0.2 // indirect
• github.com/strongo/random v0.0.1 // indirect
• github.com/strongo/slice v0.1.2 // indirect