[lldb][test] Mark TestGetBaseName.py as expected failure on Windows

TestGetBaseName.py introduced in PR #155939 is failing on windows
LLDB bots. This patch adds @expectedFailureAll(oslist=["windows"])
decorator to mark it as an expected failure on Windows to make
buildbots green while the underlying issue is investigated.

(see: https://lab.llvm.org/buildbot/#/builders/141/builds/11176).

Author: omjavaid

lldb/test/API/python_api/basename/TestGetBaseName.py

@@ -15,6 +15,7 @@ def setUp(self):
         TestBase.setUp(self)
         self.main_source_file = lldb.SBFileSpec("main.cpp")
 
+    @expectedFailureAll(oslist=["windows"])
     def test(self):
         """Test SBFunction.GetBaseName() and SBSymbol.GetBaseName()"""
         self.build()