### 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
info = self.user_info()
        overwrite = None
        try:
            ssh_key_file = self.get_ssh_key_path()
        except Exception as e:
            return (1, '', to_native(e))
        ssh_dir = os.path.dirname(ssh_key_file)
        if not os.path.exists(ssh_dir):
            if self.module.check_mode:
                return (0, '', '')
            try:
                os.mkdir(ssh_dir, int('0700', 8))
                os.chown(ssh_dir, info[2], info[3])
            except OSError as e:
                return (1, '', 'Failed to create %s: %s' % (ssh_dir, to_native(e)))
        if os.path.exists(ssh_key_file):
            if self.force:
                
                overwrite = 'y'
            else:
                return (None, 'Key already exists, use "force: yes" to overwrite', '')
        cmd = [self.module.get_bin_path('ssh-keygen', True)]
        cmd.append('-t')
        cmd.append(self.ssh_type)
        if self.ssh_bits > 0:
            cmd.append('-b')