Update using-macos.adoc

Author: anthony-j-castro

docs/guides/modules/execution-managed/pages/using-macos.adoc

@@ -12,7 +12,7 @@ You can use the macOS execution environment to run your xref:orchestrate:jobs-st
 jobs:
   build:
     macos:
-      xcode: 16.4.0
+      xcode: 26.3.0
     resource_class: m4pro.medium
 
     steps:
@@ -39,7 +39,7 @@ include::ROOT:partial$execution-resources/macos-resource-table.adoc[]
 jobs:
   build:
     macos:
-      xcode: 16.4.0
+      xcode: 26.3.0
     resource_class: m4pro.medium
 ----
 
@@ -218,7 +218,7 @@ version: 2.1
 jobs:
   build-and-test:
     macos:
-      xcode: 16.4.0
+      xcode: 26.3.0
     environment:
       HOMEBREW_NO_AUTO_UPDATE: 1
     steps:
@@ -257,7 +257,7 @@ version: 2.1
 jobs:
   build-and-test:
     macos:
-      xcode: 16.4.0
+      xcode: 26.3.0
     environment:
       FL_OUTPUT_DIR: output