Removing Iron since it is EOL

Author: danthony06

.github/workflows/main.yml

@@ -9,8 +9,6 @@ jobs:
         env:
           - {ROS_DISTRO: humble, ROS_REPO: testing}
           - {ROS_DISTRO: humble, ROS_REPO: main}
-          - {ROS_DISTRO: iron, ROS_REPO: testing}
-          - {ROS_DISTRO: iron, ROS_REPO: main}
           - {ROS_DISTRO: jazzy, ROS_REPO: testing, PIP_BREAK_SYSTEM_PACKAGES: True}
           - {ROS_DISTRO: jazzy, ROS_REPO: main, PIP_BREAK_SYSTEM_PACKAGES: True}
           - {ROS_DISTRO: rolling, ROS_REPO: testing, PIP_BREAK_SYSTEM_PACKAGES: True}