Ignore the free-threaded Windows build output directories

PCbuild/python.props places free-threaded builds in win32t, amd64t, arm32t
and arm64t, but only the GIL-enabled counterparts (win32, amd64, arm32,
arm64) were listed in .gitignore, so a --disable-gil build leaves its
output visible to git.

Author: gianghungtien

.gitignore

@@ -124,10 +124,14 @@ PCbuild/*-pgo
 PCbuild/*.VC.db
 PCbuild/*.VC.opendb
 PCbuild/amd64/
+PCbuild/amd64t/
 PCbuild/arm32/
+PCbuild/arm32t/
 PCbuild/arm64/
+PCbuild/arm64t/
 PCbuild/obj/
 PCbuild/win32/
+PCbuild/win32t/
 Tools/unicode/data/
 /autom4te.cache
 /build/