Require `return` in all match branches

Before the parser only checked if the catch-all branch has a return in
order to determine if the entire match block has a return.

This code block was assumed to always return.

    match value:
        "test":
            print("test")
        _:
            return

Now as soon as one of the branches has no return, the entire match block
is marked to not have a return.

0 files changed, 0 insertions, 0 deletions