Fix npm's package.json permissions

[disconnect3d]

Changed created file permissions from 644 (-w----r--) to 0644 (rw-r--r--) when calling WriteFile(...).

PoC:

dc@jhtc:~/gogo$ cat main.go
package main

import "io/ioutil"

func main() {
    ioutil.WriteFile("644", []byte("content"), 644)
    ioutil.WriteFile("0644", []byte("content"), 0644)
}
dc@jhtc:~/gogo$ go run main.go
dc@jhtc:~/gogo$ ls -la
total 28
drwxrwxr-x   2 dc dc  4096 Jun  9 16:42 .
drwxr-xr-x 124 dc dc 12288 Jun  9 16:42 ..
-rw-r--r--   1 dc dc     7 Jun  9 16:42 0644
--w----r--   1 dc dc     7 Jun  9 16:42 644
-rw-rw-r--   1 dc dc   156 Jun  9 16:42 main.go

[paganotoni]

Thanks for this one @disconnect3d !