Add logging handler

The lastResort handler is used by default. This might lead to unexpected
results because the lastResort handler has the WARNING log-level.

https://docs.python.org/3/library/logging.html#logging.lastResort

conda-store-server/conda_store_server/server/app.py

@@ -365,6 +365,7 @@ def start(self):
             # Note: the logger needs to be defined here for the output to show
             # up, self.log doesn't work here either
             logger = logging.getLogger("app")
+            logger.addHandler(logging.StreamHandler())
             logger.setLevel(self.log_level)
             logger.info(f"Starting server on {self.address}:{self.port}")