Windows 7: gen-crl always prompts for over-write

[TinCanTech]

Because easyrsa tries to preserve file permissions, when generating a new CRL;

easy-rsa/easyrsa3/easyrsa

Lines 3239 to 3242 in 7da361d

	if [ -r "$out_file" ]; then
	cp -p "$out_file" "$out_file_tmp" || \
	warn "Failed to preserve CRL file permissions."
	fi

Windows 7 always prompts before over-writing the temp-file.

This does not happen using windows-latest on GHA.