custom EditProfile in Django forms, submit button not working

I created EditProfile FORMs, in my forms.py file:

 from django.contrib.auth.forms import UserChangeForm
 from korisnici.models import CustomKorisnici
 from django import forms



class EditProfile(UserChangeForm):
    email = forms.EmailField(widget=forms.EmailInput(attrs={'class': 'form-control'}))
    first_name = forms.CharField(max_length=100, widget=forms.TextInput(attrs={'class': 'form-control'}))
    last_name = forms.CharField(max_length=100, widget=forms.TextInput(attrs={'class': 'form-control'}))
    phone_number = forms.CharField(max_length=100, widget=forms.TextInput(attrs={'class': 'form-control'}))
    bio = forms.CharField(max_length=100, widget=forms.TextInput(attrs={'class': 'form-control'}))
    phone_number = forms.CharField(max_length=100, widget=forms.TextInput(attrs={'class': 'form-control'}))

    class Meta:
        model = CustomKorisnici
        fields = ('username', 'first_name', 'last_name', 'email','bio','phone_number','profile_image')

    def __init__(self, *args, **kwargs):
        super(EditProfile, self).__init__(*args, **kwargs)
        self.fields['username'].widget.attrs['class'] = 'form-control'
        self.fields['phone_number'].required = False
        self.fields['profile_image'].required = False
        self.fields['bio'].required = False

After I run a default Django form in my HTML file(edit_profile.html):

<div class="form-group">
 <div class="container">
   <div class="form">
      <form method="post" enctype="multipart/form-data">
       {% csrf_token %}
       {{ form.as_p }}
        <button id="btn" class="btn" type="submit">Edit Profile</button>
      </form>
    </div>
   </div>
 </div>

When I click on submit button, it is working fine, my profile page was edit and data is change in base. But when I customize my form in bootstrap, the submission button is not doing anything. Here is my bootstrap form:

<form method="post" enctype="multipart/form-data">
  {% csrf_token %}
  <div class="form-group">
    <label >Username</label>
    <input type="text" class="form-control"  name="username">
  </div>
  <div class="form-group">
    <label >First name</label>
    <input type="text" class="form-control"  name="first_name">
  </div>
  <div class="form-group">
    <label >Last name</label>
    <input type="text" class="form-control"  name="last_name">
  </div>
  <div class="form-group">
    <label >Email </label>
    <input type="email" class="form-control"  name="email">
  </div>
  <div class="form-group">
    <label >Biography </label>
    <input type="text" class="form-control"  name="bio">
  </div>
  <div class="form-group">
    <label >Phone number</label>
    <input type="text" class="form-control"  name="phone_number">
  </div>
  <div class="form-group">
    <label >Profile image</label>
    <input type="file" class="form-control"  name="profile_image">
  </div>

  <button id="btn" class="btn" type="submit">Edit Profile</button>
</form>

and view.py:

 class UserEditProfileView(generic.UpdateView):
    form_class = EditProfile
    template_name = 'registration/edit_profile.html'
    success_url = reverse_lazy('home')

    def get_object(self):
       return self.request.user

use tag

<form method="post" enctype="multipart/form-data">
{% csrf_token %}
<div class="form-group">
<label >Username</label>
<input type="text" class="form-control"  name="username">{{ form.first_name }}
</div>
...ecc
<button id="btn" class="btn" type="submit">Edit Profile</button>
</form>