ci: Update safari version (#28720)

Author: mmalerba

test/browser-providers.js

@@ -6,7 +6,7 @@
  */
 const browserConfig = {
   'iOS15': {unitTest: {target: 'saucelabs'}},
-  'Safari15': {unitTest: {target: 'browserstack'}},
+  'Safari16': {unitTest: {target: 'browserstack'}},
 };
 
 /** Exports all available custom Karma browsers. */

test/karma-browsers.json

@@ -8,11 +8,11 @@
     "platformName": "iOS",
     "deviceName": "iPhone 13 Pro Max Simulator"
   },
-  "BROWSERSTACK_SAFARI15": {
+  "BROWSERSTACK_SAFARI16": {
     "base": "BrowserStack",
     "browser": "Safari",
-    "browser_version": "15.0",
+    "browser_version": "16.0",
     "os": "OS X",
-    "os_version": "Monterey"
+    "os_version": "Ventura"
   }
 }