swap staticmethod/lru_cache

The test suite breaks with python < 3.10 reporting this
```
[...]
setupsrc/pypdfium2_setup/packaging_base.py:110: in <module>
    class PdfiumVer:
setupsrc/pypdfium2_setup/packaging_base.py:117: in PdfiumVer
    @staticmethod
/opt/hostedtoolcache/Python/3.7.17/x64/lib/python3.7/functools.py:493:
in decorating_function
wrapper = _lru_cache_wrapper(user_function, maxsize, typed,
_CacheInfo)
E   TypeError: the first argument must be callable
[...]
ERROR tests_old/test_setup.py - TypeError: the first argument must be
callable
```

setupsrc/pypdfium2_setup/packaging_base.py

@@ -113,8 +113,8 @@ class PdfiumVer:
     V_KEYS = ("major", "minor", "build", "patch")
 
     # TODO consider cached property?
-    @functools.lru_cache(maxsize=1)
     @staticmethod
+    @functools.lru_cache(maxsize=1)
     def get_latest():
         git_ls = run_cmd(["git", "ls-remote", f"{ReleaseRepo}.git"], cwd=None, capture=True)
         tag = git_ls.split("\t")[-1]