[roll] Roll third_party/googletest Use static_cast instead of ImplicitCast_ for character conversions

Clang has recently added "warnings when mixing different charN_t types" [1].
The rationale is that "charN_t represent code units of different UTF encodings.
Therefore the values of 2 different charN_t objects do not represent the same
characters."

Note that the warning here may be legitimate - from https://github.com/google/googletest/issues/4762:
"[...] This is incorrect for values that do not represent valid codepoints."

For the time being, silence the warning by being more explicit about the
conversion being intentional by using static_cast.

Link: https://github.com/llvm/llvm-project/pull/138708 [1]
PiperOrigin-RevId: 760644157
Original-Revision: fa8438ae6b70c57010177de47a9f13d7041a6328

Roller-URL: https://cr-buildbucket.appspot.com/build/8714427821072509281
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I891e3bb2ea031823477f4f0499af9d65d7f75d83
Reviewed-on: https://fuchsia-review.googlesource.com/c/sdk-samples/getting-started/+/1280129
Commit-Queue: GI Roller <global-integration-roller@fuchsia-infra.iam.gserviceaccount.com>
diff --git a/third_party/googletest b/third_party/googletest
index 5719306..fa8438a 160000
--- a/third_party/googletest
+++ b/third_party/googletest
@@ -1 +1 @@
-Subproject commit 571930618fa96eabcd05b573285edbee9fc13bae
+Subproject commit fa8438ae6b70c57010177de47a9f13d7041a6328