pw_env_setup: Add placeholder arm.json file

Bug: 599
Change-Id: Icedd9d8e00b6c1d5f4583cafa1f42838ad9b6f8d
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/80600
Pigweed-Auto-Submit: Rob Mohr <mohrr@google.com>
Reviewed-by: Erik Gilling <konkers@google.com>
Commit-Queue: Rob Mohr <mohrr@google.com>
diff --git a/pw_env_setup/py/pw_env_setup/cipd_setup/arm.json b/pw_env_setup/py/pw_env_setup/cipd_setup/arm.json
new file mode 100644
index 0000000..0d4f101
--- /dev/null
+++ b/pw_env_setup/py/pw_env_setup/cipd_setup/arm.json
@@ -0,0 +1,2 @@
+[
+]