googletest/README.libaom: fix path to LICENSE

The file is under src/ not at the top level. This fixes a warning in
a Chromium tool (depot_tools/metadata/scan.py).

Bug: 482449277
Change-Id: I091fab6463692c9cc170cf267980ef17f3ba217d

third_party/googletest/README.libaom

diff --git a/third_party/googletest/README.libaom b/third_party/googletest/README.libaom
index 2b898a2..a7d7e7b 100644
--- a/third_party/googletest/README.libaom
+++ b/third_party/googletest/README.libaom
@@ -5,7 +5,7 @@
 Update Mechanism: Manual
 Revision: 58d77fa8070e8cec2dc1ed015d66b454c8d78850
 License: BSD-3-Clause
-License File: LICENSE
+License File: src/LICENSE
 Shipped in Chromium: no
 Security Critical: no