Remove Iron from Nightly CI (#277)

Author: pablogs9

.github/workflows/nightly.yml

@@ -14,7 +14,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        branch: [iron, rolling, jazzy, humble]
+        branch: [rolling, jazzy, humble]
         idf_target: [ esp32, esp32s2, esp32c3, esp32s3, esp32c6]
         idf_version: [ "espressif/idf:release-v4.4", "espressif/idf:release-v5.2" ]
         exclude: