Update googletest to 1.18.0 and SIMDe to 0.8.2.

Googletest 1.18 asks for CMake 3.13 or newer, so configuring the tests no longer warns that CMake compatibility below 3.10 is deprecated.

Co-authored-by: Cursor <cursoragent@cursor.com>

test/googletest/docs/platforms.md

@@ -1,35 +1,8 @@
 # Supported Platforms
 
-GoogleTest requires a codebase and compiler compliant with the C++11 standard or
-newer.
-
-The GoogleTest code is officially supported on the following platforms.
-Operating systems or tools not listed below are community-supported. For
-community-supported platforms, patches that do not complicate the code may be
-considered.
-
-If you notice any problems on your platform, please file an issue on the
-[GoogleTest GitHub Issue Tracker](https://github.com/google/googletest/issues).
-Pull requests containing fixes are welcome!
-
-### Operating systems
-
-*   Linux
-*   macOS
-*   Windows
-
-### Compilers
-
-*   gcc 5.0+
-*   clang 5.0+
-*   MSVC 2015+
-
-**macOS users:** Xcode 9.3+ provides clang 5.0+.
-
-### Build systems
-
-*   [Bazel](https://bazel.build/)
-*   [CMake](https://cmake.org/)
-
-Bazel is the build system used by the team internally and in tests. CMake is
-supported on a best-effort basis and by the community.
+GoogleTest follows Google's
+[Foundational C++ Support Policy](https://opensource.google/documentation/policies/cplusplus-support).
+See
+[this table](https://github.com/google/oss-policies-info/blob/main/foundational-cxx-support-matrix.md)
+for a list of currently supported versions compilers, platforms, and build
+tools.