Support for floating point timeout values

[darintay]

Describe the bug
Floating point timeouts are unsupported in fakeredis, they are reported as negative values and error out. They are supported in real Redis.

From the Redis docs, e.g.: https://redis.io/commands/blpop/
The timeout argument is interpreted as a double value specifying the maximum number of seconds to block

To Reproduce

>>> import fakeredis
>>> r = fakeredis.FakeRedis()
>>> r.blpop("mylist1", 1.1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.10/dist-packages/redis/commands/core.py", line 2594, in blpop
    return self.execute_command("BLPOP", *keys)
  File "/usr/local/lib/python3.10/dist-packages/redis/client.py", line 536, in execute_command
    return conn.retry.call_with_retry(
  File "/usr/local/lib/python3.10/dist-packages/redis/retry.py", line 46, in call_with_retry
    return do()
  File "/usr/local/lib/python3.10/dist-packages/redis/client.py", line 537, in <lambda>
    lambda: self._send_command_parse_response(
  File "/usr/local/lib/python3.10/dist-packages/redis/client.py", line 513, in _send_command_parse_response
    return self.parse_response(conn, command_name, **options)
  File "/usr/local/lib/python3.10/dist-packages/redis/client.py", line 553, in parse_response
    response = connection.read_response()
  File "/home/ubuntu/.local/lib/python3.10/site-packages/fakeredis/_server.py", line 120, in read_response
    raise response
redis.exceptions.ResponseError: timeout is negative
>>> r.blpop("mylist1", 1)
>>> 

Expected behavior
Floating point timeouts should work.

Additional context
Thanks for making this great tool, super useful for tests!

[cunla]

Thanks for bringing this up. I will fix it during the weekend.