Fix -Wincompatible-pointer-type errors with gcc 14.

```
In file included from /usr/lib/perl5/core_perl/CORE/perl.h:6225,
                 from RabbitMQ.xs:2:
RabbitMQ.xs: In function 'XS_Net__AMQP__RabbitMQ_get_rpc_timeout':
RabbitMQ.xs:1962:29: error: passing argument 2 of 'Perl_newRV_noinc' from incompatible pointer type [-Wincompatible-pointer-types]
 1962 |       RETVAL = newRV_noinc( output );
      |                             ^~~~~~
      |                             |
      |                             HV * {aka struct hv *}
/usr/lib/perl5/core_perl/CORE/embed.h:423:72: note: in definition of macro 'newRV_noinc'
  423 | # define newRV_noinc(a)                         Perl_newRV_noinc(aTHX_ a)
      |                                                                        ^
In file included from /usr/lib/perl5/core_perl/CORE/perl.h:7870:
/usr/lib/perl5/core_perl/CORE/sv_inline.h:972:34: note: expected 'SV *' {aka 'struct sv *'} but argument is of type 'HV *' {aka 'struct
hv *'}
  972 | Perl_newRV_noinc(pTHX_ SV *const tmpRef)
      |                        ~~~~~~~~~~^~~~~~
```

```
/usr/lib/perl5/core_perl/CORE/sv.h:1438:33: error: passing argument 2 of 'Perl_hv_common_key_len' from incompatible pointer type [-Wincompatible-pointer-types]
 1438 | #    define SvRV(sv) ((sv)->sv_u.svu_rv)
/usr/lib/perl5/core_perl/CORE/embed.h:293:78: note: in definition of macro 'hv_common_key_len'
  293 | # define hv_common_key_len(a,b,c,d,e,f)         Perl_hv_common_key_len(aTHX_ a,b,c,d,e,f)
      |                                                                              ^
/usr/lib/perl5/core_perl/CORE/hv.h:556:5: note: in expansion of macro 'hv_fetch'
  556 |     hv_fetch((hv), ASSERT_IS_LITERAL(key), (sizeof(key)-1), (lval))
      |     ^~~~~~~~
RabbitMQ.xs:98:31: note: in expansion of macro 'hv_fetchs'
   98 |  do { SV **v; if(NULL != (v = hv_fetchs(hv, #name, 0))) name = SvIV(*v); } while(0)
      |                               ^~~~~~~~~
RabbitMQ.xs:1992:7: note: in expansion of macro 'int_from_hv'
 1992 |       int_from_hv(SvRV(args), tv_usec);
      |       ^~~~~~~~~~~
RabbitMQ.xs:1992:19: note: in expansion of macro 'SvRV'
 1992 |       int_from_hv(SvRV(args), tv_usec);
      |                   ^~~~
/usr/lib/perl5/core_perl/CORE/proto.h:1592:34: note: expected 'HV *' {aka 'struct hv *'} but argument is of type 'SV *' {aka 'struct sv *'}
 1592 | Perl_hv_common_key_len(pTHX_ HV *hv, const char *key, I32 klen_i32, const int action, SV *val, const U32 hash);
      |                              ~~~~^~
```

--- Net-AMQP-RabbitMQ-2.40012-origin/RabbitMQ.xs
+++ Net-AMQP-RabbitMQ-2.40012/RabbitMQ.xs
@@ -95,11 +95,11 @@
 }
 
 #define int_from_hv(hv,name) \
- do { SV **v; if(NULL != (v = hv_fetchs(hv, #name, 0))) name = SvIV(*v); } while(0)
+ do { SV **v; if(NULL != (v = hv_fetchs((HV*)hv, #name, 0))) name = SvIV(*v); } while(0)
 #define double_from_hv(hv,name) \
- do { SV **v; if(NULL != (v = hv_fetchs(hv, #name, 0))) name = SvNV(*v); } while(0)
+ do { SV **v; if(NULL != (v = hv_fetchs((HV*)hv, #name, 0))) name = SvNV(*v); } while(0)
 #define str_from_hv(hv,name) \
- do { SV **v; if(NULL != (v = hv_fetchs(hv, #name, 0))) name = SvPV_nolen(*v); } while(0)
+ do { SV **v; if(NULL != (v = hv_fetchs((HV*)hv, #name, 0))) name = SvPV_nolen(*v); } while(0)
 #define has_valid_connection(conn) \
  ( amqp_get_socket( conn ) != NULL && amqp_get_sockfd( conn ) > -1 )
 #define assert_amqp_connected(conn) \
@@ -1959,7 +1959,7 @@
       output = newHV();
       hv_stores(output, "tv_sec", newSVi64( timeout_tv->tv_sec ));
       hv_stores(output, "tv_usec", newSVi64( timeout_tv->tv_usec ));
-      RETVAL = newRV_noinc( output );
+      RETVAL = newRV_noinc( (SV*)output );
     }
   OUTPUT:
     RETVAL