sums: Use Digest::SHA instead of Digest::SHA1

So I'll be able to get rid of old cruft in tests/perlmodules.t .

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tests/perlmodules.t: Delete Digest::SHA1

libdigest-sha1-perl changed name to libdigest-sha-perl a while ago. I
don't think I use any systems that old anymore, so it should be safe to
remove it now.

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