too many errors

[sofianehammami]

Hi, I'm a newbie in go and I want to use the cli of this repository on centos 7
As stated in the README file, I executed the command line go get github.com/google/easypki/cmd/easypki which is supposed to get the cli. But I'm getting this huge error stack
I'm using go version 1.15.2

[root@localhost opt]# go get github.com/google/easypki/cmd/easypki
# github.com/google/easypki/cmd/easypki
/root/go/src/github.com/google/easypki/cmd/easypki/main.go:52:37: cannot slice c.Args() (type cli.Args)
/root/go/src/github.com/google/easypki/cmd/easypki/main.go:126:14: cannot range over c.Args() (type cli.Args)
/root/go/src/github.com/google/easypki/cmd/easypki/main.go:159:5: app.Author undefined (type *cli.App has no field or method Author)
/root/go/src/github.com/google/easypki/cmd/easypki/main.go:160:5: app.Email undefined (type *cli.App has no field or method Email)
/root/go/src/github.com/google/easypki/cmd/easypki/main.go:171:17: cannot use cli.StringFlag literal (type cli.StringFlag) as type cli.Flag in slice literal:
        cli.StringFlag does not implement cli.Flag (Apply method has pointer receiver)
/root/go/src/github.com/google/easypki/cmd/easypki/main.go:175:4: unknown field 'EnvVar' in struct literal of type cli.StringFlag
/root/go/src/github.com/google/easypki/cmd/easypki/main.go:184:4: cannot use r.revoke (type func(*cli.Context)) as type cli.ActionFunc in field value
/root/go/src/github.com/google/easypki/cmd/easypki/main.go:189:4: cannot use r.crl (type func(*cli.Context)) as type cli.ActionFunc in field value
/root/go/src/github.com/google/easypki/cmd/easypki/main.go:191:16: cannot use cli.IntFlag literal (type cli.IntFlag) as type cli.Flag in slice literal:
        cli.IntFlag does not implement cli.Flag (Apply method has pointer receiver)
/root/go/src/github.com/google/easypki/cmd/easypki/main.go:196:5: cannot use caNameFlag (type cli.StringFlag) as type cli.Flag in slice literal:
        cli.StringFlag does not implement cli.Flag (Apply method has pointer receiver)
/root/go/src/github.com/google/easypki/cmd/easypki/main.go:196:5: too many errors

If I'm doing things wrong please provide how to build the project.