SADDEX - implement set with support for expiring members

[cunla]

Fix #347

[github-actions]

Coverage report:

Name                                                    Stmts   Miss Branch BrPart  Cover
-----------------------------------------------------------------------------------------
fakeredis/__init__.py                                      22      5      2      1    75%
fakeredis/_basefakesocket.py                              251     10     94     10    94%
fakeredis/_command_args_parsing.py                         71      2     42      2    96%
fakeredis/_commands.py                                    301     11     96      7    95%
fakeredis/_connection.py                                   95     10     30      7    86%
fakeredis/_fakesocket.py                                   10      0      0      0   100%
fakeredis/_helpers.py                                     170      4     60      3    97%
fakeredis/_msgs.py                                        101      0      0      0   100%
fakeredis/_server.py                                       60      5     12      3    89%
fakeredis/_tcp_server.py                                   95     14     34     12    78%
fakeredis/_valkey.py                                       36     16      4      1    52%
fakeredis/aioredis.py                                     152     14     40      8    88%
fakeredis/commands_mixins/__init__.py                      21      5      0      0    76%
fakeredis/commands_mixins/bitmap_mixin.py                 200      4     92      2    98%
fakeredis/commands_mixins/connection_mixin.py              33      1      6      1    95%
fakeredis/commands_mixins/generic_mixin.py                268     56    106     12    75%
fakeredis/commands_mixins/geo_mixin.py                    148     11     52      5    89%
fakeredis/commands_mixins/hash_mixin.py                   204      8     56      6    95%
fakeredis/commands_mixins/list_mixin.py                   245      8     96      8    95%
fakeredis/commands_mixins/pubsub_mixin.py                 119      7     36      8    88%
fakeredis/commands_mixins/scripting_mixin.py              175      7     68      7    94%
fakeredis/commands_mixins/server_mixin.py                  89      6     22      4    91%
fakeredis/commands_mixins/set_mixin.py                    145     14     38      6    87%
fakeredis/commands_mixins/sortedset_mixin.py              420     16    146     16    94%
fakeredis/commands_mixins/streams_mixin.py                258     28    116     29    85%
fakeredis/commands_mixins/string_mixin.py                 235      8    100      9    95%
fakeredis/commands_mixins/transactions_mixin.py            74      7     20      3    89%
fakeredis/geo/__init__.py                                   3      0      0      0   100%
fakeredis/geo/geohash.py                                   45      0     18      0   100%
fakeredis/geo/haversine.py                                 10      0      0      0   100%
fakeredis/model/__init__.py                                 7      0      0      0   100%
fakeredis/model/_expiring_members_set.py                   66     15     12      2    76%
fakeredis/model/_hash.py                                   61      0      8      0   100%
fakeredis/model/_stream.py                                325     14    110     11    94%
fakeredis/model/_timeseries_model.py                      173     13     70      4    91%
fakeredis/model/_topk.py                                   85      1     28      2    97%
fakeredis/model/_zset.py                                   68      0     14      0   100%
fakeredis/server_specific_commands/__init__.py              2      0      0      0   100%
fakeredis/server_specific_commands/dragonfly_mixin.py      19     10      2      0    43%
fakeredis/stack/__init__.py                                27     14      4      0    42%
fakeredis/stack/_bf_mixin.py                              122     18     48      9    78%
fakeredis/stack/_cf_mixin.py                              132     27     38      9    75%
fakeredis/stack/_cms_mixin.py                              79      0     38      0   100%
fakeredis/stack/_json_mixin.py                            327     12    114      9    95%
fakeredis/stack/_tdigest_mixin.py                         173     32     90     29    77%
fakeredis/stack/_timeseries_mixin.py                      337     45    168     33    83%
fakeredis/stack/_topk_mixin.py                             77     15     34     15    73%
-----------------------------------------------------------------------------------------
TOTAL                                                    6136    493   2164    293    90%