**Describe the bug**
Using /etc/nanomq_pwd.conf for storing username/password combinations.
1. If the password contains only numbers, the user is ignored
2. If the username contains one or more dots (.), the user is ignored.

**Expected behavior**
User/Password combination works as expected, even with only numbers in the password or dots in the username.

**Actual Behavior**
Users **test** and **test.test** are ignored.
```
2024-03-23 22:15:43 [823] INFO  /nanomq/nng/src/supplemental/nanolib/conf.c:978 print_auth_conf: [0] username: test1
2024-03-23 22:15:43 [823] INFO  /nanomq/nng/src/supplemental/nanolib/conf.c:978 print_auth_conf: [1] username: test2
```


**To Reproduce**
_/etc/nanomq_pwd.conf_
```
test1: ABCD
test: 12345
test2: ABCD
test.test: ABCD
```

**Environment Details**
 - NanoMQ v0.21.8-7
 - Docker image from official Docker Hub

Users in pwd-file ignored
This is a GitHub Issue
repo:nanomq
owner:emqx
Title : Users in pwd-file ignored
Issue date:

--- start body ---
**Describe the bug**
Using /etc/nanomq_pwd.conf for storing username/password combinations.
1. If the password contains only numbers, the user is ignored
2. If the username contains one or more dots (.), the user is ignored.

**Expected behavior**
User/Password combination works as expected, even with only numbers in the password or dots in the username.

**Actual Behavior**
Users **test** and **test.test** are ignored.
```
2024-03-23 22:15:43 [823] INFO  /nanomq/nng/src/supplemental/nanolib/conf.c:978 print_auth_conf: [0] username: test1
2024-03-23 22:15:43 [823] INFO  /nanomq/nng/src/supplemental/nanolib/conf.c:978 print_auth_conf: [1] username: test2
```


**To Reproduce**
_/etc/nanomq_pwd.conf_
```
test1: ABCD
test: 12345
test2: ABCD
test.test: ABCD
```

**Environment Details**
 - NanoMQ v0.21.8-7
 - Docker image from official Docker Hub

--- end body ---
