boot-qemu.py: Use .open() with pathlib object

Clears up ruff warning:

  boot-qemu.py:211:14: PTH123 `open("foo")` should be replaced by `Path("foo").open()`

Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Author: nathanchance

boot-qemu.py

@@ -208,7 +208,7 @@ def get_smp_value(args):
     # CONFIG_NR_CPUS then get the actual value if possible.
     config_nr_cpus = 8
     if config_file:
-        with open(config_file, encoding='utf-8') as file:
+        with config_file.open(encoding='utf-8') as file:
             for line in file:
                 if "CONFIG_NR_CPUS=" in line:
                     config_nr_cpus = int(line.split("=", 1)[1])