fix: prevent duplicate log output via propagate=False

[spalen0]

Problem

morpho.markets_v2 (and any other child logger whose parent also uses utils.logger.get_logger) prints every log line twice.

Root cause

get_logger attaches a StreamHandler to each named logger but leaves propagate = True. When a child logger (e.g. morpho.markets_v2) imports a module that creates a parent logger (e.g. morpho from protocols/morpho/markets.py), the same record is emitted by both handlers.

Fix

Set logger.propagate = False inside get_logger when we install our own handler, so each record is only emitted once.

Verification

Ran uv run protocols/morpho/markets_v2.py before and after; duplicate lines are gone.