Use tempfile.mkstemp instead of tempfile.mktemp.

The `tempfile.mktemp` function is [deprecated](https://docs.python.org/3/library/tempfile.html#tempfile.mktemp) due to [security issues](https://cwe.mitre.org/data/definitions/377.html).

The switch is easy to do.

PiperOrigin-RevId: 420363556
Change-Id: I3225120cd6545462174641581a365ead0eb179c3

tensorflow/python/saved_model/load_test.py

@@ -207,8 +207,8 @@ def test_control_outputs(self, cycles):
         imported_graph.control_outputs)
 
   def _make_asset(self, contents):
-    filename = tempfile.mktemp(prefix=self.get_temp_dir())
-    with open(filename, "w") as f:
+    fd, filename = tempfile.mkstemp(prefix=self.get_temp_dir())
+    with os.fdopen(fd, "w") as f:
       f.write(contents)
     return filename
 
@@ -2494,8 +2494,8 @@ def layer_variable_creator(next_creator, **kwargs):
     load_and_run_module(export_dir, weight_size)
 
   def _make_asset(self, contents):
-    filename = tempfile.mktemp(prefix=self.get_temp_dir())
-    with open(filename, "w") as f:
+    fd, filename = tempfile.mkstemp(prefix=self.get_temp_dir())
+    with os.fdopen(fd, "w") as f:
       f.write(contents)
     return filename