pw_protobuf: Remove code-generation timestamps

Google discourages timestamps in generated files due to determinism
concerns, and the timestamp comments in Pigweed's proto codegen don't
seem necessary. This change removes those timestamps to ensure the
generated files don't change between builds unless the inputs or build
settings have changed.

Bug: b/234067834
Change-Id: I4e480f93fe41671ab8ad4e36c9ef578855fcdc8b
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/96161
Reviewed-by: Ted Pudlik <tpudlik@google.com>
Reviewed-by: Alexei Frolov <frolv@google.com>
Commit-Queue: Matthias Guenther <mrguenther@google.com>

pw_protobuf/py/pw_protobuf/codegen_pwpb.py

@@ -14,7 +14,6 @@
 """This module defines the generated code for pw_protobuf C++ classes."""
 
 import abc
-from datetime import datetime
 import enum
 # Type ignore here for graphlib-backport on Python 3.8
 from graphlib import CycleError, TopologicalSorter  # type: ignore
@@ -2208,7 +2207,6 @@ def generate_code_for_package(file_descriptor_proto, package: ProtoNode,
 
     output.write_line(f'// {os.path.basename(output.name())} automatically '
                       f'generated by {PLUGIN_NAME} {PLUGIN_VERSION}')
-    output.write_line(f'// on {datetime.now()}')
     output.write_line('#pragma once\n')
     output.write_line('#include <algorithm>')
     output.write_line('#include <array>')