libgav1_tests.cmake,dsp_test: add missing dep

dsp_test transitively depends on absl::time via the libgav1_tests_utils
target; fixes build with -DLIBGAV1_THREADPOOL_USE_STD_MUTEX=1

PiperOrigin-RevId: 354435495
Change-Id: I44a7bc9bb27e27ea31bbff692bbe54f3443c7811
diff --git a/tests/libgav1_tests.cmake b/tests/libgav1_tests.cmake
index 60b4ccf..d4d499a 100644
--- a/tests/libgav1_tests.cmake
+++ b/tests/libgav1_tests.cmake
@@ -234,6 +234,7 @@
                          libgav1_utils
                          LIB_DEPS
                          absl::strings
+                         absl::time
                          ${libgav1_common_test_absl_deps}
                          libgav1_gtest
                          libgav1_gtest_main)