[core] Remove references to deleted setup.py (#6757)

script/build_codeowners.py

@@ -28,7 +28,7 @@ BASE = """
 # the integration's code owner is automatically notified.
 
 # Core Code
-setup.py @esphome/core
+pyproject.toml @esphome/core
 esphome/*.py @esphome/core
 esphome/core/* @esphome/core
 

script/ci-custom.py

@@ -229,7 +229,6 @@ def lint_ext_check(fname):
         "docker/ha-addon-rootfs/**",
         "docker/*.py",
         "script/*",
-        "setup.py",
     ]
 )
 def lint_executable_bit(fname):