Form().EncType() doesn't result in setting enctype in rendered form.

[sesopenko]

When calling app.Form().EncType("multipart/form-data") the encoding type isn't set on the form.

Code to reproduce:

package main

import (
	"github.com/maxence-charriere/go-app/v6/pkg/app"
)

type order struct {
	app.Compo
	firstName string
	lastName  string
}

func (o *order) Render() app.UI {
	return app.Div().Body(
		app.Main().Body(
			app.H1().Body(
				app.Text("icanhazprint?"),
			),
			app.Form().
				Method("post").Action("/api/v1/create-order").
				EncType("multipart/form-data").
				Body(
					app.Input().Value(o.firstName).Placeholder("What is your first name?").AutoFocus(true),
					app.Input().Value(o.lastName).Placeholder("What is your last name?"),
					app.Input().Type("file").Name("image").Placeholder("File"),
					app.Input().Type("submit").Value("Submit"),
				),
		),
	)
}

func main() {
	app.Route("/", &order{})
	app.Run()
}

Expected results:

Chrome Version 83.0.4103.116 (Official Build) (64-bit) (Ubuntu, installed from deb)

form has enctype="multipart/form-data" attribute.

<form action="/api/v1/create-order" enctype="multipart/form-data" method="post" _lpchecked="1"><input value="" placeholder="What is your first name?" autofocus=""><input value="" placeholder="What is your last name?"><input placeholder="File" type="file"><input type="submit" value="Submit"></form>

Actual Results:

Form is missing enctype="multipart/form-data" attribute.

<form action="/api/v1/create-order" method="post" _lpchecked="1"><input value="" placeholder="What is your first name?" autofocus=""><input value="" placeholder="What is your last name?"><input placeholder="File" type="file"><input type="submit" value="Submit"></form>

[sesopenko]

go version go1.14.2 linux/amd64 if that helps.

What's strange is that Method() works correctly but EncType() doesn't. I dug around in html.go and saw that Method() and EncType() set attributes the same way.

I also tried app.Input().Type("submit").Value("Submit").FormEncType("multipart/form-data"), but that didn't work either. Digging around in html.go there doesn't appear to be a Submit type, just Button and Input.