Cache get_native_microarchitecture

No tests for this one, just a sample run:

In [1]: import importlib

In [2]: mod = importlib.import_module("src.mpsd_software_manager.mpsd_software")

In [3]: mod.set_up_logging('INFO')

In [4]: mod.get_native_microarchitecture()
2023-06-28 11:46:14,057    INFO  |  !<meta>microarchitecture:zen3</meta>!
Out[4]: 'zen3'

In [5]: mod.get_native_microarchitecture()
Out[5]: 'zen3'

Closes #20 (closed)

src/mpsd_software_manager/mpsd_software.py

@@ -16,6 +16,7 @@ from pathlib import Path
 from typing import List, Tuple, Union
 import re
 import shutil
+from functools import cache
 
 # If 'rich' is available ("pip install rich" or "apt-get install python3-rich"),
 # then use coloured output, otherwise proceed as before
@@ -790,6 +791,7 @@ def prepare_environment(mpsd_release: str, root_dir: Path) -> List[str]:
     return available_package_sets
 
 
+@cache
 def get_native_microarchitecture():
     """Return native microarchitecture.