Some source files are not well formatted

[hangxie]

With go 1.16:

$ go fmt ./...
$ git status
On branch master
Your branch is up to date with 'origin/master'.

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git restore <file>..." to discard changes in working directory)
    modified:   marshal/unmarshal.go
    modified:   parquet/GoUnusedProtection__.go
    modified:   parquet/parquet-consts.go
    modified:   parquet/parquet.go

[hangxie]

I still think it's better to have a format target in Makefile like https://github.com/xitongsys/parquet-go/pull/367/files#diff-76ed074a9305c04054cdebb9e9aad2d818052b07091de1f20cad0bbac34ffb52R8, not everybody setup their editors to auto-formatting.

[xitongsys]

fixed. thanks !