Update nightly health check workflow

Author: calvincestari

.github/workflows/nightly-health-check.yml

@@ -6,11 +6,12 @@ on:
     - cron: "0 7 * * *"
 
 env:
-  XCODE_VERSION: "16.4"
+  MACOS_VERSION: "macos-26"
+  XCODE_VERSION: "26.1"
 
 jobs:
   tuist-generation:
-    runs-on: macos-15
+    runs-on: ${{ env.MACOS_VERSION }}
     timeout-minutes: 8
     name: Run Tuist Generation
     steps:
@@ -31,7 +32,7 @@ jobs:
         key: ${{ github.run_id }}-dependencies
 
   run-swift-builds:
-    runs-on: macos-15
+    runs-on: ${{ env.MACOS_VERSION }}
     timeout-minutes: 15
     strategy:
       fail-fast: false
@@ -53,7 +54,7 @@ jobs:
         cd ${{ matrix.package }} && swift build
 
   build-and-unit-test:
-    runs-on: macos-15
+    runs-on: ${{ env.MACOS_VERSION }}
     needs: tuist-generation
     timeout-minutes: 20
     strategy:
@@ -153,7 +154,7 @@ jobs:
           TestResults/ResultBundle.zip
 
   run-codegen-test-configurations:
-    runs-on: macos-15
+    runs-on: ${{ env.MACOS_VERSION }}
     timeout-minutes: 20
     name: Codegen Test Configurations - macOS
     steps:
@@ -168,7 +169,7 @@ jobs:
         ./scripts/run-test-codegen-configurations.sh -t
   
   send-slack-status-notification:
-    runs-on: macos-15
+    runs-on: ${{ env.MACOS_VERSION }}
     if: ${{ always() }}
     timeout-minutes: 5
     needs: [tuist-generation, run-swift-builds, build-and-unit-test, run-codegen-test-configurations]