Ensure pet binary is marked as executable (#23680)

Author: DonJayamanne

noxfile.py

@@ -5,6 +5,7 @@
 import pathlib
 import nox
 import shutil
+import sys
 import sysconfig
 import uuid
 
@@ -78,6 +79,9 @@ def azure_pet_build_after(session: nox.Session):
     bin_dest = dest_dir / "bin" / bin_name
     shutil.copyfile(abs_bin_path, bin_dest)
 
+    if sys.platform != "win32":
+        shutil.chmod(bin_dest, 0o755)
+
 
 @nox.session()
 def native_build(session: nox.Session):