win32: adjust max path length for SHA256

The longest path within a git repository is now a SHA256 format
packfile. Adjust our max length checking to match.

tests/libgit2/repo/init.c

@@ -727,7 +727,7 @@ void test_repo_init__defaultbranch_config_empty(void)
 void test_repo_init__longpath(void)
 {
 #ifdef GIT_WIN32
-	size_t padding = CONST_STRLEN("objects/pack/pack-.pack.lock") + GIT_OID_SHA1_HEXSIZE;
+	size_t padding = CONST_STRLEN("objects/pack/pack-.pack.lock") + GIT_OID_MAX_HEXSIZE;
 	size_t max, i;
 	git_str path = GIT_STR_INIT;
 	git_repository *one = NULL, *two = NULL;