Ensure dotfiles are also included in release archives

[stertooy]

No description provided.

[james-d-mitchell]

This'll work to resolve my issue, not sure if it might have further implications I'm not aware of though. Thanks @stertooy

[stertooy]

The current situation is a bit contradictory, since using cp -r * target doesn't copy dotfiles in the current directory, but does copy over dotfiles from subdirectories. And we also do some cleanup that includes a lot of dotfiles (which weren't copied over anyway):

release-pkg/action.yml

Lines 148 to 157 in db30629

	echo "::group::Cleanup git and github related files"
	rm -rvf .git* .hg* .cvs* .circleci
	echo "::group::Cleanup codecov, travis, azure-pipelines"
	rm -fv .codecov.* .travis.* .appveyor.* azure-pipelines.*
	rm -fv .gaplint.*
	rm -fv requirements.txt
	echo "::group::Cleanup macOS metadata"
	find . -name .DS_Store -exec rm -f {} +

Perhaps we should just choose a particular route to take w.r.t. dotfiles:

1. Never add them to a release by default, but provide an input that lets users specify dotfiles to explicitly add
2. Copy them over by default, unless it's on our "removal list" (i.e. the code above).

Personally I'm more a fan of option 2. I'd prefer to have this action create functional releases with no extra effort for authors, at the cost of perhaps some unneeded dotfiles slipping through.