capabilities plugin: remove warning about "leaking" a pointer to a local variable.

capabilities plugin: remove warning about "leaking" a pointer to a local variable.

```
src/capabilities.c: In function 'cap_http_handler':
src/capabilities.c:209:23: error: storing the address of local variable '({anonymous})' in '*connection_state' [-Werror=dangling-pointer=]
  209 |     *connection_state = &(int){44};
      |     ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~
src/capabilities.c:209:31: note: '({anonymous})' declared here
  209 |     *connection_state = &(int){44};
      |                               ^
src/capabilities.c:209:31: note: 'connection_state' declared here
```