pw_presubmit: Remove requirements.txt reference

Pigweed no longer has a requirements.txt, so it should't be added to the
virtualenv invocation called from pw_presubmit.

Change-Id: I7569c84e5545cd6a6f3db3332f87ec9a5b6b7245
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/34120
Pigweed-Auto-Submit: Armando Montanez <amontanez@google.com>
Reviewed-by: Rob Mohr <mohrr@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/pw_presubmit/py/pw_presubmit/environment.py b/pw_presubmit/py/pw_presubmit/environment.py
index d0d7f37..7af5d52 100644
--- a/pw_presubmit/py/pw_presubmit/environment.py
+++ b/pw_presubmit/py/pw_presubmit/environment.py
@@ -86,7 +86,6 @@
         'python3',
         virtualenv_source,
         f'--venv_path={output_directory}',
-        f'--requirements={virtualenv_source / "requirements.txt"}',
         *(f'--requirements={x}' for x in requirements),
         *(f'--gn-target={t}' for t in gn_targets),
     )