Remove misleading message from CI

The CI jobs do not usually have mypy_cache volume created and
almost all jobs print misleading "mypy_cache_volume" error at
the beginning.

This is a noise - we are not interested in this stderr printed
message - we are only interested in returncode from checking
if it exists.

dev/breeze/src/airflow_breeze/utils/path_utils.py

@@ -256,10 +256,18 @@ def create_volume_if_missing(volume_name: str):
     from airflow_breeze.utils.run_utils import run_command
 
     res_inspect = run_command(
-        cmd=["docker", "volume", "inspect", volume_name], stdout=subprocess.DEVNULL, check=False
+        cmd=["docker", "volume", "inspect", volume_name],
+        stdout=subprocess.DEVNULL,
+        stderr=subprocess.DEVNULL,
+        check=False,
     )
     if res_inspect.returncode != 0:
-        run_command(cmd=["docker", "volume", "create", volume_name], check=True)
+        run_command(
+            cmd=["docker", "volume", "create", volume_name],
+            stdout=subprocess.DEVNULL,
+            stderr=subprocess.DEVNULL,
+            check=True,
+        )
 
 
 def create_static_check_volumes():