### Summary

When using the user module to modify password_expire_min=0, the processing result does not meet expectations .
I guess the problem is caused by the following code in the user module.
```
    # deal with password expire min
    if user.password_expire_min:
        if user.user_exists():
            (rc, out, err) = user.set_password_expire_min()
```
Modifying to the following  code may fix this problem.
```
    # deal with password expire min
    if user.password_expire_min is not None:
        if user.user_exists():
            (rc, out, err) = user.set_password_expire_min()
```

### Issue Type

Bug Report

### Component Name

user

### Ansible Version

```console
$ ansible --version
ansible [core 2.11.1] 
  config file = None
  configured module search path = ['/home/betadmin/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /app/python3/lib/python3.8/site-packages/ansible
  ansible collection location = /home/betadmin/.ansible/collections:/usr/share/ansible/collections
  executable location = /app/python3/bin/ansible
  python version = 3.8.5 (default, Sep 18 2020, 14:55:53) [GCC 4.8.5 20150623 (Red Hat 4.8.5-16)]
  jinja version = 2.11.2
  libyaml = False
```


### Configuration

```console
$ ansible-config dump --only-changed
```


### OS / Environment

RHEL 7.4

### Steps to Reproduce

- name: Edit password_expire_min
  user:
    name: test
    password_expire_min: 0



### Expected Results

Minimum number of days between password change	: 0


### Actual Results


Minimum number of days between password change	: 2


### Code of Conduct

- [X] I agree to follow the Ansible Code of Conduct
'''Hide or show user on login window according SELF.SYSTEM.
        Returns 0 if a change has been made, None otherwise.'''
        plist_file = '/Library/Preferences/com.apple.loginwindow.plist'
        
        cmd = ['defaults', 'read', plist_file, 'HiddenUsersList']
        (rc, out, err) = self.execute_command(cmd, obey_checkmode=False)
        
        
        
        
        
        
        hidden_users = []
        for x in out.splitlines()[1:-1]:
            try:
                x = x.split('"')[1]
            except IndexError:
                x = x.strip()
            hidden_users.append(x)
        if self.system:
            if self.name not in hidden_users:
                cmd = ['defaults', 'write', plist_file, 'HiddenUsersList', '-array-add', self.name]
                (rc, out, err) = self.execute_command(cmd)
                if rc != 0: