Add missing spectators include

[nekiro]

Pull Request Prelude

• I have followed proper The Forgotten Server code styling.
• I have read and understood the contribution guidelines before making this PR.
• I am aware that this PR may be closed if the above-mentioned criteria are not fulfilled.

Changes Proposed

Add missing include, because it apparently fails to find SpectatorVec in map.cpp/h

Issues addressed:
Master branch doesn't compile

11:57:16:406	1>C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.41.34120\include\utility(459,10): error C2079: 'std::pair<const Position,SpectatorVec>::second' uses undefined class 'SpectatorVec'
11:57:16:485	1>(compiling source file '/theforgo.A10F9657/x64/Debug/unity_4QKKRKOVXFEDFVS0.cpp')
11:57:16:485	1>    C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.41.34120\include\utility(459,10):
11:57:16:485	1>    the template instantiation context (the oldest one first) is
11:57:16:485	1>        D:\repos\forgottenserver-fork\src\map.h(260,17):

How to test:
Try to compile