//tools/base:requirements.update fails to build due to missing pyproject.toml input file

[chipmunkie]

Title: Python dependencies update fails due to missing input file

Description:

What issue is being seen?
Python dependencies update detailed in https://github.com/envoyproxy/nighthawk/blob/main/docs/root/updating_envoy_dependency.md#step-11 fails due to missing input file '//tools/base:pyproject.toml'

Reproduction steps:

Include sample requests, environment, etc. All data and inputs
required to reproduce the bug.

~/nighthawk$ bazel run //tools/base:requirements.update

INFO: Invocation ID: 344a0345-9242-41c9-97c2-2bc455bf3393
INFO: Build option --action_env has changed, discarding analysis cache.
INFO: Analyzed target //tools/base:requirements.update (138 packages loaded, 4350 targets configured).
INFO: Found 1 target...
ERROR: /usr/local/google/home/amerlan/nighthawk/tools/base/BUILD:8:25: Middleman _middlemen/tools_Sbase_Srequirements.update-runfiles failed: missing input file '//tools/base:pyproject.toml'
ERROR: /usr/local/google/home/amerlan/nighthawk/tools/base/BUILD:8:25: Middleman _middlemen/tools_Sbase_Srequirements.update-runfiles failed: 1 input file(s) do not exist
Target //tools/base:requirements.update failed to build
Use --verbose_failures to see the command lines of failed build steps.
ERROR: /usr/local/google/home/amerlan/nighthawk/tools/base/BUILD:8:25 Middleman _middlemen/tools_Sbase_Srequirements.update-runfiles failed: 1 input file(s) do not exist
INFO: Elapsed time: 8.325s, Critical Path: 0.44s
INFO: 4 processes: 4 internal.
FAILED: Build did NOT complete successfully
ERROR: Build failed. Not running target

[chipmunkie]

bazelbuild/rules_python#1519 changes the way the requirements file is provided when adding support for *.toml files.