Make test a bit more reproducible for the future

Signed-off-by: Marek Kubica <marek@tarides.com>

test/blackbox-tests/test-cases/default-cache.t

@@ -1,5 +1,6 @@
 The dune cache should be enabled by default
-  $ echo "(lang dune 3.16)" > dune-project
+
+  $ echo "(lang dune 3.17)" > dune-project
 
   $ cat > dune << EOF
   > (library
@@ -11,22 +12,24 @@ The dune cache should be enabled by default
   > EOF
 
 Set up cache directory
+
   $ export DUNE_CACHE_ROOT=$(pwd)/dune_test_cache
   $ mkdir $DUNE_CACHE_ROOT
-
   $ DUNE_CACHE=disabled dune build
   $ ls $DUNE_CACHE_ROOT
+
 We have not written anything to the cache yet.
 
 Change source files to force a recompilation
+
   $ cat > foo.ml << EOF
   > let f x y = x - y
   > EOF
-
   $ dune build
-  $ ls $DUNE_CACHE_ROOT
+  $ ls $DUNE_CACHE_ROOT | sort
   files
   meta
   temp
   values
+
 Cache has been written to!