build-unit-test-docker: update googletest

Googletest 1.14 has issues with clang-18.  Update to 1.15.2 which
seems to no longer have the issues.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ic31cd021ea17ba6d1a9f81399f8deaa86bdb5900
diff --git a/scripts/build-unit-test-docker b/scripts/build-unit-test-docker
index a07a9f5..f7de137 100755
--- a/scripts/build-unit-test-docker
+++ b/scripts/build-unit-test-docker
@@ -130,7 +130,7 @@
         ],
     ),
     "google/googletest": PackageDef(
-        rev="v1.14.0",
+        rev="v1.15.2",
         build_type="cmake",
         config_env=["CXXFLAGS=-std=c++20"],
         config_flags=["-DTHREADS_PREFER_PTHREAD_FLAG=ON"],