CI: use latest Lua 5.4; test Windows

[hishamhm]

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[hishamhm]

@alerque I'm knees-deep in a chain of somewhat circular dependencies for updates related to the recent breakage of the LuaJIT download URLs.

This is a snapshot of the personal txt file I'm using to keep the track of the dance I'm going through:

[ ] luarocks/luarocks
   [ ] PR #639 teal
      [ ] lunarmodules/compat53 problems

[ ] leafo/gh-actions-lua
   [ ] PR #50 hishamhm:master - waiting for merge

[ ] leafo/gh-actions-luarocks
   [ ] prepare an update PR

[ ] teal-language/tl
   [ ] PR #334 next
      [ ] hishamhm/gh-actions-luarocks problems
         [ ] luajit build is broken, can't find LUA_LIBDIR

[ ] lunarmodules/lua-compat-5.3
   [ ] push new version
      [x] math.tointeger
      [ ] file:write

[x] hisham/gh-actions-lua
   [x] LuaJIT rolling release support
   [x] PR #50 to leafo/gh-actions-lua

[ ] luarocks/cluacov
   [x] push release 0.1.4
      [x] update code for Lua 5.4.7
      [x] update code for LuaJIT rolling release
   [ ] PR #6 ci-lua-5.4.7
      [ ] update CI to test both

[ ] hisham/gh-actions-luarocks
   [ ] LuaJIT rolling release support

I'll get this one merged once I gets its CI going green, and keep moving on with this list.