gh-138432: Improved invalid path checking in zoneinfo.reset_tzpath() (GH-138433)

* Improve error messages for path-like relative paths and path-like bytes paths.
* TZPATH is now always a tuple of strings.

Lib/zoneinfo/_tzpath.py

@@ -13,6 +13,13 @@ def _reset_tzpath(to=None, stacklevel=4):
                 + f"not {type(tzpaths)}: {tzpaths!r}"
             )
 
+        tzpaths = [os.fspath(p) for p in tzpaths]
+        if not all(isinstance(p, str) for p in tzpaths):
+            raise TypeError(
+                "All elements of a tzpath sequence must be strings or "
+                "os.PathLike objects which convert to strings."
+            )
+
         if not all(map(os.path.isabs, tzpaths)):
             raise ValueError(_get_invalid_paths_message(tzpaths))
         base_tzpath = tzpaths