ci: clean up downloaded event-codes header after generation #71

Job	Run time
ci / Change Detection	5s
ci / Setup Matrix	0s
ci / Release Please	0s
ci / Docs	0s
ci / Markdownlint	0s
ci / StyLua	0s
ci / Detect Metadata	0s
ci / Luacheck	0s
ci / Run Tests (${{ matrix.os }}, ${{ matrix.lua-version }})	0s
ci / Publish to LuaRocks	0s
	5s

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