fixes development rockspec for MinGW and adds Windows / macOS to the test matrix

[luau-project]

Description

This PR has two purposes:

1. fixes the development rockspec (lua-zlib-scm-0.rockspec) for MinGW / MinGW-w64 on Windows, and simplifies the build on Unix or MSVC on Windows;
2. adds macos-14 and windows-2025 to the test matrix.

Changes on lua-zlib-scm-0.rockspec

1. The entry libdirs = { "$(ZLIB_LIBDIR)" } was added to the default build rule. This change allows to build lua-zlib with zlib installed at custom places on both Unix and Windows through the command

luarocks make lua-zlib-scm-0.rockspec ZLIB_DIR=/path/to/zlib

Note

The old setting only linked with zlib from system directories (/usr/lib and /usr/local/lib).

2. The platform-override entry for mingw solves the linking problem for both MinGW / MinGW-w64 on Windows. Here, I applied a clever trick: on Windows, MinGW / MinGW-w64 can link libraries by the feeding the DLL to the linker. Then, grounded on the fact that a standard zlib installation always emits a DLL named libzlib1.dll or zlib1.dll, the build rules of LuaRocks allows it to link lua-zlib with zlib via the DLL.

Changes on .github/workflows/test.yml

1. added macos-14 and windows-2025 to the test matrix;
2. building zlib 1.3.1 from source code on Windows;
3. caching zlib tarballs to avoid flooding (DOS) zlib website https://zlib.net;
4. builds of (PUC-Rio) Lua 5.4, 5.3, 5.2 and 5.1 uses MSVC toolchain on Windows;
5. builds of LuaJIT and OpenResty uses the standard MinGW-w64 toolchain provided by GitHub on Windows.

Notes

1. If any user complains about not being able to build lua-zlib with MinGW / MinGW-w64 through lua-zlib-scm-0.rockspec, most likely it is related to a misconfiguration of LuaRocks. Also, anytime it happens, feel free to mention me through a @ , because I think I can help;
2. Even though it is not present in the workflow, I tested the changed rockspec with multiple MinGW / MinGW-w64 providers (GitHub provider, MSYS2 provider, sourceforge provider), and they are all working fine;
3. In my opinion, it might be a good time to push a new rockspec to https://luarocks.org/ based on lua-zlib-scm-0.rockspec.

[luau-project]

Fixes #73

[brimworks]

Thank you for the contribution!