[sr-dev] [kamailio/kamailio] detailed_ipv4_type func pkg memory leak. (Issue #3159)

### Description

when call detailed_ipv4_type function, pkg memory leak. ```c detailed_ipv4_type($si,"$var(iptype)"); ```

### Troubleshooting

#### Reproduction just call detailed_ipv4_type function.

#### Debugging Data

``` ALERT: qm_sums: qm_sums(): count= 48161 size= 1789640 bytes from core: core/rvalue.c: rval_get_str(1293)

```

### Possible Solutions

ip address string not free in rval_get_str() function. [s->s=pkg_malloc(tmp.len+1/* 0 term */);](https://github.com/kamailio/kamailio/blob/1ddc27f199061025a6a43da3e8a1388fca...) need call pkg_free() free memory.

### Additional Information test 3 version. ``` kamailio 5.5.4 kamailio 5.4.8 kamailio 5.3.9 ```

* **Operating System**: ``` buster 10 ubuntu 20.04 ```