firebase13: bump minimum macOS to 11.0 and watchOS to 8.0 (#16551)

FirebaseCore.podspec

@@ -26,9 +26,9 @@ Firebase Core includes FIRApp and FIROptions which provide central configuration
   s.social_media_url = 'https://twitter.com/Firebase'
 
   ios_deployment_target = '15.0'
-  osx_deployment_target = '10.15'
+  osx_deployment_target = '11.0'
   tvos_deployment_target = '15.0'
-  watchos_deployment_target = '7.0'
+  watchos_deployment_target = '8.0'
 
   s.ios.deployment_target = ios_deployment_target
   s.osx.deployment_target = osx_deployment_target
@@ -73,7 +73,7 @@ Firebase Core includes FIRApp and FIROptions which provide central configuration
     unit_tests.scheme = { :code_coverage => true }
     unit_tests.platforms = {
       :ios => ios_deployment_target,
-      :osx => '10.15',
+      :osx => osx_deployment_target,
       :tvos => tvos_deployment_target
     }
     unit_tests.source_files = [