release: Release with separate SHA256SUMS and sig files

This allows us to remove the rfc4880 EOL hacks and release with a
SHA256SUMS.asc file that's a combination of all signer signatures.

contrib/guix/guix-attest

@@ -159,20 +159,6 @@ Hint: You may wish to remove the existing attestations and their signatures by
 EOF
 }
 
-# Given a document with unix line endings (just <LF>) in stdin, make all lines
-# end in <CR><LF> and make sure there's no trailing <LF> at the end of the file.
-#
-# This is necessary as cleartext signatures are calculated on text after their
-# line endings are canonicalized.
-#
-# For more information:
-#     1. https://security.stackexchange.com/a/104261
-#     2. https://datatracker.ietf.org/doc/html/rfc4880#section-7.1
-#
-rfc4880_normalize_document() {
-    sed 's/$/\r/' | head -c -2
-}
-
 echo "Attesting to build outputs for version: '${VERSION}'"
 echo ""
 
@@ -188,7 +174,6 @@ mkdir -p "$outsigdir"
         cat "${noncodesigned_fragments[@]}" \
             | sort -u \
             | sort -k2 \
-            | rfc4880_normalize_document \
                 > "$temp_noncodesigned"
         if [ -e noncodesigned.SHA256SUMS ]; then
             # The SHA256SUMS already exists, make sure it's exactly what we
@@ -216,7 +201,6 @@ mkdir -p "$outsigdir"
         cat "${sha256sum_fragments[@]}" \
             | sort -u \
             | sort -k2 \
-            | rfc4880_normalize_document \
                 > "$temp_all"
         if [ -e all.SHA256SUMS ]; then
             # The SHA256SUMS already exists, make sure it's exactly what we