Update ICU

Rolling v8/third_party/icu: https://chromium.googlesource.com/chromium/deps/icu/+log/50ec7b3..b3070c5

[build] Suppress -Wenum-constexpr-conversion (Gulfem Savrun Yeniceri)
https://chromium.googlesource.com/chromium/deps/icu/+/b3070c5

Use LTO bug workaround in Fuchsia build (Roland McGrath)
https://chromium.googlesource.com/chromium/deps/icu/+/4404a4d

R=v8-waterfall-sheriff@grotations.appspotmail.com,mtv-sf-v8-sheriff@grotations.appspotmail.com,ftang@chromium.org

Change-Id: I9f7ffb1b34c1068a1577e6bda164da55f28601d2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3829353
Bot-Commit: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Commit-Queue: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#82452}

DEPS

@@ -240,7 +240,7 @@ deps = {
   'third_party/googletest/src':
     Var('chromium_url') + '/external/github.com/google/googletest.git' + '@' + 'af29db7ec28d6df1c7f0f745186884091e602e07',
   'third_party/icu':
-    Var('chromium_url') + '/chromium/deps/icu.git' + '@' + '50ec7b3822a90d73aa761b21fc941b485a1cb9d6',
+    Var('chromium_url') + '/chromium/deps/icu.git' + '@' + 'b3070c52557323463e6b9827e2343e60e1b91f85',
   'third_party/instrumented_libraries':
     Var('chromium_url') + '/chromium/src/third_party/instrumented_libraries.git' + '@' + 'e09c4b66b6e87116eb190651421f1a6e2f3b9c52',
   'third_party/ittapi': {