Use OS11 as host for WebRTC Chromium FYI ios-simulator

(xcode13 requires Mac OS 11)

Bug: b/210105045
Change-Id: I5f45432254babd653ecd25332c51a1c766cdb51a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3341551
Reviewed-by: Mirko Bonadei <mbonadei@chromium.org>
Auto-Submit: Björn Terelius <terelius@chromium.org>
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/main@{#951997}

ios/build/bots/chromium.webrtc.fyi/WebRTC Chromium FYI ios-simulator.json

@@ -26,21 +26,21 @@
       "include": "webrtc_tests.json",
       "device type": "iPhone 11",
       "os": "14.4",
-      "host os": "Mac-10.15|Mac-11",
+      "host os": "Mac-11",
       "pool": "chromium.tests"
     },
     {
       "include": "webrtc_tests.json",
       "device type": "iPhone X",
       "os": "14.4",
-      "host os": "Mac-10.15|Mac-11",
+      "host os": "Mac-11",
       "pool": "chromium.tests"
     },
     {
       "include": "webrtc_tests.json",
       "device type": "iPad Air (3rd generation)",
       "os": "14.4",
-      "host os": "Mac-10.15|Mac-11",
+      "host os": "Mac-11",
       "pool": "chromium.tests"
     }
   ]