windows: properly test against Python version string

The value passed in here is `XY` not `X.Y`. That means that our
`pathcch` and `shlwapi` annotations were incorrect prior to this
change.

This fixes bugs in the following commits:

* 9fb81f1
* cc9da9c
* 4ff995a

Author: indygreg

cpython-windows/build.py

@@ -1876,11 +1876,11 @@ def find_additional_dependencies(project: pathlib.Path):
     ]
 
     # pathcch is required on 3.9+ and its presence drops support for Windows 7.
-    if python_majmin != "3.8":
+    if python_majmin != "38":
         res["core"]["links"].append({"name": "pathcch", "system": True})
 
     # shlwapi was dropped from 3.9.9+.
-    if python_majmin == "3.8":
+    if python_majmin == "38":
         res["core"]["links"].append({"name": "shlwapi", "system": True})
 
     # Copy files for extensions into their own directories.