borgmatic: fix systemd service

due to https://github.com/borgmatic-collective/borgmatic/commit/2e9f70d49647d47fb4ca05f428c592b0e4319544
there is another "sleep", which is now wrongly substituted.

This fixes the error:
Failed to inhibit: Invalid what specification
/nix/store/if12v01xkqladifvk8yqjdpbp6sisg74-coreutils-9.1/bin/sleep:shutdown

Signed-off-by: Florian Brandes <florian.brandes@posteo.de>

pkgs/tools/backup/borgmatic/default.nix

@@ -34,11 +34,13 @@ python3Packages.buildPythonApplication rec {
 
     mkdir -p $out/lib/systemd/system
     cp sample/systemd/borgmatic.timer $out/lib/systemd/system/
+    # there is another "sleep", so choose the one with the space after it
+    # due to https://github.com/borgmatic-collective/borgmatic/commit/2e9f70d49647d47fb4ca05f428c592b0e4319544
     substitute sample/systemd/borgmatic.service \
                $out/lib/systemd/system/borgmatic.service \
                --replace /root/.local/bin/borgmatic $out/bin/borgmatic \
                --replace systemd-inhibit ${systemd}/bin/systemd-inhibit \
-               --replace sleep ${coreutils}/bin/sleep
+               --replace "sleep " "${coreutils}/bin/sleep "
   '';
 
   passthru.tests.version = testers.testVersion { package = borgmatic; };