Update test for `git_str` usage instead of `git_buf`

See commit f0e693b1

tests/worktree/worktree.c

@@ -297,19 +297,19 @@ void test_worktree_worktree__add_no_checkout(void)
 	git_worktree *wt;
 	git_repository *wtrepo;
 	git_index *index;
-	git_buf path = GIT_BUF_INIT;
+	git_str path = GIT_STR_INIT;
 	git_worktree_add_options opts = GIT_WORKTREE_ADD_OPTIONS_INIT;
 
 	opts.checkout_opts.checkout_strategy = GIT_CHECKOUT_NONE;
 
-	cl_git_pass(git_buf_joinpath(&path, fixture.repo->workdir, "../worktree-no-checkout"));
+	cl_git_pass(git_str_joinpath(&path, fixture.repo->workdir, "../worktree-no-checkout"));
 	cl_git_pass(git_worktree_add(&wt, fixture.repo, "worktree-no-checkout", path.ptr, &opts));
 
 	cl_git_pass(git_repository_open(&wtrepo, path.ptr));
 	cl_git_pass(git_repository_index(&index, wtrepo));
 	cl_assert_equal_i(git_index_entrycount(index), 0);
 
-	git_buf_dispose(&path);
+	git_str_dispose(&path);
 	git_worktree_free(wt);
 	git_repository_free(wtrepo);
 }