[path_provider] Update Windows implementation version (flutter#3541)

Author: stuartmorgan-g

packages/path_provider/path_provider/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 2.0.0-nullsafety.1
+
+* Require latest path_provider_windows to avoid potential issues
+  with breaking changes in `ffi` and `win32`.
+
 ## 2.0.0-nullsafety
 
 * Migrate to null safety.

packages/path_provider/path_provider/pubspec.yaml

@@ -1,7 +1,7 @@
 name: path_provider
 description: Flutter plugin for getting commonly used locations on host platform file systems, such as the temp and app data directories.
 homepage: https://github.com/flutter/plugins/tree/master/packages/path_provider/path_provider
-version: 2.0.0-nullsafety
+version: 2.0.0-nullsafety.1
 
 flutter:
   plugin:
@@ -24,7 +24,7 @@ dependencies:
   path_provider_platform_interface: ^2.0.0-nullsafety
   path_provider_macos: ^0.0.5-nullsafety
   path_provider_linux: ^0.2.0-nullsafety
-  path_provider_windows: ^0.1.0-nullsafety
+  path_provider_windows: ^0.1.0-nullsafety.3
 
 dev_dependencies:
   integration_test: