build: Drop an errant requirements.txt file.

This file should not exist, we do not use a top-level requirements file
in this repo to manage dependencies.  All dependency files should live
in the `requirements` folder.

requirements.txt

@@ -1,9 +0,0 @@
-#
-# This file is autogenerated by pip-compile with Python 3.11
-# by the following command:
-#
-#    pip-compile
-#
-
-# The following packages are considered to be unsafe in a requirements file:
-# setuptools