pw_env_setup: Delete requirements.txt

Change-Id: I232a64f59515472268cc541812e7bd6262dcd683
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/29760
Pigweed-Auto-Submit: Rob Mohr <mohrr@google.com>
Reviewed-by: Wyatt Hepler <hepler@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/pw_env_setup/py/pw_env_setup/virtualenv_setup/requirements.txt b/pw_env_setup/py/pw_env_setup/virtualenv_setup/requirements.txt
deleted file mode 100644
index e69de29..0000000
--- a/pw_env_setup/py/pw_env_setup/virtualenv_setup/requirements.txt
+++ /dev/null