borgbackup: fix ssh binary location

Otherwise, borg might be unable to find its location

pkgs/tools/backup/borg/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, python3Packages, acl, lz4, openssl }:
+{ stdenv, fetchurl, python3Packages, acl, lz4, openssl, openssh }:
 
 python3Packages.buildPythonApplication rec {
   name = "borgbackup-${version}";
@@ -27,6 +27,10 @@ python3Packages.buildPythonApplication rec {
     export BORG_LZ4_PREFIX="${lz4.dev}"
   '';
 
+  makeWrapperArgs = [
+    ''--prefix PATH ':' "${openssh}/bin"''
+  ];
+
   postInstall = ''
     make -C docs singlehtml
     mkdir -p $out/share/doc/borg